Even after several years, the ASUS Xonar DX sound card remains a very attractive proposition for purchase. ASUS products in the field of computer audio in general very quickly became popular and in demand, since the manufacturer really offers a worthwhile implementation for reasonable money.
Of course, the Xonar DX is in many ways a stripped-down version, but for the average user the card can be a real find. Nevertheless, the solution is based on fairly serious digital-to-analog converters Cirrus Logic CS4398 and CS4362. They support 192 kHz 24-bit operating mode and provide a signal-to-noise ratio of 120 and 114 dB, respectively. All this gives the manufacturer grounds to claim that in some respects the ASUS Xonar DX is tens of times better than built-in audio. There is a bit of slyness in this, but this fact does not detract from the advantages of the interface.
Therefore, our Xonar DX review will try to figure out whether this sound card is really as good as the common built-in HD Audio.
Contents of delivery
The completeness of the card is not particularly outstanding. In the box you can find:
- replaceable socket for compact cases with two screws;
- adapter for supplying additional power;
- adapter for optical cable;
- signal cable 3.5 mm – 2 RCA;
- instructions and driver disk.
As you can see, there is not even a complete set of cords for connecting a multi-channel system. For example, the packaging of Creative cards of the appropriate level is often much more serious.
Card design
ASUS uses its own proprietary chip, labeled AV100, as the main sound processor. Its real developer is the company C-Media, and its design of the chip was called OxygenHD CMI8787. By the way, the differences between ASUS AV100 and ASUS AV200, which are included in more expensive cards, are very relative, and they come down only to algorithms for working with software. ASUS Xonar DX has a PCI Express x1 interface, and the PEX812 controller from PLX Technology is used for communication.
The Cirrus Logic CS5361 chip works as an analog-to-digital converter. To reproduce the sound of the front channels, Cirrus Logic CS4398 192 kHz 24 bits with 120 dB SNR is used. For all others, Cirrus Logic CS4362 114 dB SNR was used. The microcircuits are quite good, one might say, top-end. You can even find them in sound cards that cost several times more.
The organization of the board itself is, in our opinion, very thoughtful. A low-profile design is used, due to which ASUS Xonar DX can be installed not only in conventional desktops, but also in smaller cases. For example, good sound obviously won’t hurt in an HTPC based on mini-ITX boards.
Outputs and inputs are designed as 3.5 mm golden-colored connectors. The optical output is combined with the analog output, so a special adapter is included in the package to use it. The only thing I didn’t like was that the location was too close, because of which high-quality cables with thick plugs simply rest against each other. But again, this is a tribute to the low profile.
By the way, the board has a standard plug for connecting the front connectors on the front panel of the computer. It is very comfortable. By the way, for ASUS Xonar DX to work, additional power must be supplied to the board, for which a standard connector is used. This is installed in card readers and other small peripherals. In this case, we don’t like its implementation, because During operation, contact may be lost and the card simply stops working. I would like to see a more secure connector with a latch.
ASUS Xonar DX Software
The sound card comes with fairly convenient software that is not overly rich in settings, but allows you to quickly use all the functions. The first tab of the Xonar DX Audio Center settings allows you to select the operating mode of the audio interface. First of all, the speaker configuration and sampling frequency are set. Xonar DX can output both simple stereo and decompose the signal up to 7.1 mode.
The mixer allows you to adjust the volume of individual inputs. Naturally, this can be done for both playback and recording.
The effects tab allows you to use various ready-made presets to change the character of the sound or make such settings yourself. Here we will only say that any sound card has something similar, but few people prefer to use it.
Naturally, there are various additional features. For example, the acoustic communication suppression function, various voice presets for voice communication, and so on.
Testing and subjective opinion
To test the audio card, we used common software, performing all the preliminary settings according to the manufacturer’s methods. It must be said that the program used was first proposed by a group of developers closely associated with the famous site iXBT.com. Today it has undergone many revisions, and, in fact, is the de facto standard in amateur measurements of audio path parameters. This is largely due to the ease of use, because To get results, you actually only need software and a connecting cable.
And the presentation of the obtained data itself is organized in the best possible way. After running for a couple of minutes, the program displays a simple plate with integral ratings of the plan “excellent”, “good” or “bad”, by which you can immediately judge the quality of the device. For a more detailed study, you can look at graphs with spectra. As a result: in terms of the sum of such parameters as availability, measurement accuracy, ease of use, RMAA is the best option today. For example, ASUS uses it as an official measurement tool. The results for various operating modes can be seen below.
As you can see, the ASUS Xonar DX sound card has very impressive characteristics. In 24-bit 48 kHz mode, we were able to achieve a noise level of -111 dB, dynamic range of 111 dB, and harmonic distortion of a measly 0.0007 percent. Overall, the result is really excellent. Only the interpenetration of channels turned out to be not very good, but this can be attributed to the nuances of a particular instance or the subtleties of the computer used. In general, there are more than enough such numbers to provide an excellent sound level.
To make our results more understandable, let’s consider them in comparison with the built-in sound using the example of the Realtek ALC889 controller. The first parameter - the unevenness of the amplitude-frequency response - speaks for itself. It indicates how much the signal's decibel (sound pressure) differs from the target level at different frequencies. While this parameter is extremely important for acoustics, for modern cards it is purely nominal. For example, with ASUS Xonar DX we have +0.01, -0.07 dB. In fact it is a straight line. It is simply unrealistic to hear this difference. Built-in audio provides identical results.
The noise level characterizes the quality of the entire path, showing how large the inherent noise is in the complete absence of a signal. In our case we have -111 dB, the best controllers on motherboards give about -90 dB. This is already a very noticeable difference, showing the superiority of high-quality cards. In fact, the dynamic range also depends on this parameter, which, in simple terms, indicates the difference between the minimum and maximum signal levels that the device can reproduce. Naturally, the higher it is, the better. In our case - about 110 dB, for a good built-in audio, for example, the same ALC889 - a maximum of 90 dB.
Distortions, both harmonic and intermodulation, characterize the nonlinearity of the path. Simply put, the percentage of “garbage” in the original signal. The existing parameter at the level of 0.0007% lies in the field of theoretical research, and cannot be heard by the ear.
In fact, all these numbers are beyond the sensitivity of the human ear, but, surprisingly, there is a subjective difference. To confirm this, we conducted a subjective comparison test using KRK V8 v2 near-field monitors. The opponents were the ESI Juli@ audio interface and the built-in audio on the Realtek ALC889. When listening to various materials, we did not notice any difference between the Xonar DX and Juli@, at least not obvious. But the superiority over the ALC889 is felt. This is clearly visible in the detail of the mid frequencies.
Conclusion
As a result, we can say that in today's realities, ASUS Xonar DX is a good choice for a multimedia computer. The card is affordable, yet good at games, and provides a sound level suitable for even very serious acoustics. Naturally, you can fully use headphones.
Don't forget about additional advantages, for example, the low-profile design, which makes the solution perfect for an HTPC.
Pros:
- affordable price;
- high class converters;
- low profile design.
Minuses:
- close location of connectors;
- combined microphone and line input;
- flimsy power contact.
Price
You can buy an ASUS Xonar DX for about 2,500 rubles, and it really has few comparable worthy competitors. The closest option is probably the Creative SoundBlaster X-Fi Titanium. This card is no less versatile. It is suitable for gamers and provides a good sound level for lovers of high-quality audio.
Asus Essence One is the top product in the line of external audiophile sound cards. This is the first external consumer card in which as many as 11 replaceable operational amplifiers can be changed to tune the audio path. The card has professional XLR connectors for connecting home active studio monitors (increasingly often purchased for PCs instead of standard Hi-Fi sets). Essence One can also be useful for musicians, because it has support for ASIO 2.0 and is capable of operating up to 192 kHz 24 bits via USB with low latency. Another interesting feature, not often found among external sound cards, is that Asus Essence One can operate in external DAC mode without connecting to a computer, positioned as an “external DAC.” The analog path uses two PCM1795 chips, each of which is enabled in mono mode and provides one balanced channel to ensure record performance. In addition, there is a built-in upsampler that operates at frequencies of 352 and 384 kHz, ahead of competitors that only use 192 kHz.
Asus is quite actively developing in the market of audiophile devices. First, the company actively pushed Creative among sound cards (the release of Asus Xonar D2), and after the remaining “professional” cards like E-MU1212m, ESI Juli@ and some audiophile products like Audiotrak HD2 at the expense of Xonar Essence ST and Xonar Essence STX cards. New products, for example Onkyo SE-300, can compete with ST and STX, but only as another promising product, without any advantage over Asus, since the hardware is generally similar, and the availability for the buyer is much worse than that of Asus.
At the moment, the niche of internal cards is occupied quite tightly, but there remains a gap among external sound cards. The most striking example among external devices not from the world of professional cards is ESI Dr.DAC Prime. Prime replaced the Audiotrak Dr.DAC 2 and was not a particularly successful upgrade. On the one hand, the SRC function was added to the device, and on the other hand, they reduced the possibility of adjusting parameters using replaceable op-amps by replacing the headphone amplifier path with a soldered microcircuit. The device has become more expensive, but nothing revolutionary has appeared in it. The only thing that pleased me was its availability in our market. Asus Essence One is a logical continuation of Dr. DAC 2, where you can see the development of this ideology. According to this ideology, we have only a DAC, with the ability to reproduce a signal from digital inputs without connecting to a PC, and when connected via USB from a PC, work up to 96 kHz and 24 bits versus the standard 48 kHz and 16 bits of the nearest external sound cards. So does the Asus Essence One today: while most cards and DACs only support 96 kHz 24 bit over USB 2.0, the Asus Essence One supports 192 kHz 24 bit. Instead of five replaceable op-amps in Dr.DAC 2, you can already change 11 op-amps in Essence One. Like Prime, Essence One has an SRC function (moreover, it operates at high frequencies and proportional to the main one). Audiophile attributes have been added - an internal power supply on a toroidal transformer, instead of an external switching power supply. The dimensions and weight have increased, but is it really worth worrying about if Dr.DAC 2 and Prime still had external power and, accordingly, could be mobile devices, but not portable?
The most pleasant thing is the price, which, of course, is not ultra-low, psychologically expected at $300, but also not exorbitant at $1000, but comparable to Prime at $500. The fact that this is a mass product gives some hope that we are looking at another “killer” of famous products with price tags like phone numbers. On the other hand, the desire to get a low price tag forces the manufacturer to focus only on those parameters and features that will ensure mass sales. And here we can recall STX with 23 dB, which in fact turned out to be only at the level of 113 dB for the 44.1 kHz mode, where the record of 123 dB was only in the 96 kHz mode. Let's see what we got with the Asus Essence One.
Specifications
The summary table on official sources is somewhat chaotic (for example, the signal amplitude parameter is the same for Vpp and rms, although the relationship between them is Vrms = 0.3535Vpp), so brief characteristics are below, combined from official data and our measured ones.
Appearance
On the front panel there is an impressive looking power button with LED backlight. The Upsampling button is responsible for increasing the sampling rate. The next button switches input sources: coaxial, optical or USB input. The Mute button mutes the sound. There are two volume controls: one for line outputs, the other separately for headphone output. Levels are individually adjustable.
The rear panel contains connectors for analog line outputs, balanced XLR and unbalanced RCA. Digital outputs include coaxial, optical and USB input. Near the power connector (full-size pin with grounding) there is a switch that allows the device to work with both 220 V and 115 V. When you turn it on for the first time, it is worth checking the set value, because if the voltage is set to 115 V, the fuse inside will burn out, and until you replace it yourself, the device will not work.
Inside
Inside you can see a tight, neat installation. It was not possible to see any points on the basis of which one could suspect possible problems. For frequencies that are multiples of 44 and 48 kHz, two separate oscillators are used, 45.16 MHz and 49.15 MHz.
Unlike conventional W-shaped transformers, toroidal ones do not spread interference around themselves and are allowed in devices with dense installation. By the way, initially toroidal transformers were developed for the military industry precisely to be able to use dense mounting in compact devices. In conventional technology, W-shaped transformers prevailed, since it was permissible to place the boards at some distance from the transformer.
The second advantage of such power supply versus external or internal switching power supplies is that there is no propagation of noise throughout the general network. Quite often it happens that expensive Hi-End equipment reacts very sensitively to the presence of switching power supplies and, accordingly, does not sound so soulful, and external filters do not always save the day. Hence the main complaints about computers from which the sound is “bad”.
DSP ADI ADSP - 21261 is responsible for the main logic. It is likely that the SRC function is implemented precisely through it.
C-Media CMI 6631 is responsible for USB operation, and thanks to it, the Asus Xonar One has support for 192 kHz via USB.
The SPDIF receiver, implemented on the AKM AK4113, is responsible for transmitting digital streams from the coaxial and optical input.
The block diagram shows all the op-amps that can be changed, there are 11 of them. Next to the DSP ADI ADSP - 21261 there is an EN25F40 flash memory chip, similar to an op-amp, but it is not an op-amp. Accordingly, it is highly not recommended to change it to an op-amp...
To convert from digital to analog, two PCM1795 chips are used, each of which operates on one of the channels in PCM1795 mono mode.
Main technical characteristics of PCM1795:
- data processing: 32 bit
- dynamic range and signal-to-noise: 123 dB, (mono mode: 126 dB)
- THD+Noise: 0.0005%
- Stop Band Attenuation: 98 dB
The PCM1795 belongs to Burr-Brown's top line of DACs, where its main advantages are working with 32-bit data (not requiring conversion from 32-bit to 24-bit) and low distortion. The noise level of the PCM1795 is not the highest in the line of DACs, but its characteristics are not inferior to the top representatives from Crystal Semiconductor, AKM and Wolfson.
By default, NE5532 are located in the section of filters (1) and adders (2), these are widespread op-amps that are more preferable than 4580, however, this is not the top, to feel that everything is as it should be in the card, you should put an OPA2132 or LM4562 there , which, using Dr.Dac2 as an example, showed some of the best results in objective and subjective tests. You can try other op-amps, including quite expensive discrete op-amps from Bursone Audio, but you just have to be prepared for serious expenses.
In sections 3A and 3B there are LM4562 op-amps, which are responsible for the output gain controlled by the volume controls. Volume control is carried out through low-noise regulators from the Japanese company ALPS.
The amplifier path consists of two replaceable LME49720NA and two non-replaceable LME49600TS.
By replacing different op-amps, you can choose a more suitable sound that better matches the rest of the path.
In progress
When you turn it on for the first time, you will most likely need to update the firmware; there are detailed instructions for this. After installing the driver, an icon appears in the tray; when clicked, an information window appears. There are no settings or other controls. No problems were found during operation.
When playing from Direct Sound and WASAPI, only the playback frequency is displayed, and when playing from ASIO, the Bit Perfect indicator lights up.
ASIO
Since the card does not physically have an input, it was not possible to determine the real minimum delay (in the test via RMAA). The level of latency depends on the size of the buffer, and based on its value you can calculate the latency, however, in the Xonar series of internal cards the latency was actually higher, which was not critical for consumer cards. Low latency in ASIO is essential for musicians to play virtual instruments live.
With One, you cannot select a buffer value in samples, but only in ms, where the minimum value is 10 ms, which for a frequency of 44 kHz is similar to 440 samples. Typically, a buffer of 512 samples is considered normal, but already an extreme value for working live with instruments. Therefore, on the one hand, the minimum number is not very critical, but it could be much lower, like in professional products in the form of 2 ms or even lower. But here it is worth noting that we are talking about a USB device, where 10-20 ms is the value at which the card works without failures in the form of clicks.
When playing projects from Ableton Live at frequencies from 44 kHz to 192 kHz at the selected minimum latency of 10 ms, there were no glitches; it was clear that the bottleneck here was the laptop CPU.
Listening
Two tests were carried out: using speaker systems and headphones.
Using acoustic systems, we obtained an assessment of the sound of the device's DAC path, and using headphones, we additionally assessed the path of the built-in headphone amplifier in the Asus Essence One.
Asus Essence One vs Asus Essence STX
The circuit used a high-quality Technics SE-A5 amplifier, a Hi-End model, with a measured distortion level of no higher than 0.001% at average power. The monitors were speaker systems based on Eton8-800/37HEX + Vifa XT25. The same woofer is used in the ADAM S2.5A, and a similar tweeter is used in the BlueSky SAT 6.5 MK II satellites. For those who focus on quality = price, the cost of similar passive monitors with similar components will be approximately $2000-2500 per pair. The cost of the amplifier adjusted for inflation is $1500. The speaker impedance is 6 ohms. Additionally, Microlab Pure 1 was used (price at the time of active sales - $700).
The audition was carried out in a blind test mode. Both sources were brought to the same level with a spread of no more than a hundredth of a decibel. A separate switch on the biscuit switch was responsible for switching sources.
When the test is carried out using the sighted method, and moreover, with unregulated levels, then a large error in the result is introduced by both different psychoacoustic perception of sound at different volumes, and self-hypnosis (often depending on the type of price tag or brand preferences).
The main thing I would like to note is the different construction of the scene. In One, the scene is larger; if the distribution of sources in STX is a kind of diverging triangle, then the echelon of instruments in direct comparison are not arranged in straight rows, but in an arc. If you don’t listen too closely, you will first notice that the locations along the edges of the stereo panorama are the same (for the first row), and the center is further inland. Which is correct and which is better? It was possible to answer this question by making a comparison with a “more reference” source, but in the Hi-End and Upper Hi-Fi categories, and even with many new products, this is difficult, because it is not difficult to challenge someone’s reference standard .
Therefore, the listener should choose what suits him best - an accented and close center (usually vocals) in the case of STX, or a more distant center with an emphasis on the background and a circular panorama in the case of One. With One, the sound is perceived as less aggressive, more relaxing. Distortion, detail and reverberation are all at a similar level.
Asus Essence One and headphones
To assess the potential, we listened to both regular top-class headphones from the $300-500 category, and the highest category, from $1000. Based on the card's hardware and its large-scale production, it's fair to expect high quality from Asus One, comparable to more expensive custom-made devices from the Hi-End world. How else to evaluate quality, if not with headphones from a similar Hi-End category?
For two headphone models, a separate headphone amplifier, the studio SPL Auditor, was used as an opponent, where the sound rating was given in a blind test.
Asus Essence One and Denon AH-D2000
The power reserve is more than sufficient; no problems were felt in the sound. The pressure in the low frequency region is completely preserved, and the bass is well articulated. In principle, the D2000 can be classified as a headphone with above-average sensitivity for its class (full-size headphones with low impedance), so the rating with them is how well the amplifier performs at a low output power with a low impedance load. In this case, the weak point of the amplifiers is the possible audible background, which was not the case with the D2000. If you don’t strive for the compression “warm” sound of tube amplifiers, then the built-in amplifier in One is quite self-sufficient.
Asus Essence One and HiFiMan HE-500
There were no problems with an isodynamic load close to a capacitor load. In addition, although the HE-500 are low-impedance, their sensitivity is low for their class (full-size headphones with low impedance). There were no problems with sufficient power; the One amplifier coped well with the “pumping”. The development of reverberations is at a more than good level. For those who are not very knowledgeable about the types of headphones, isodynamic headphones are the closest to electrostatic headphones. Among the inexpensive models, there are Fostex RP lines, which are inferior in the quantity and quality of low frequencies due to the use of membranes of a smaller area
Asus Essence One and Sennheiser HD 800
HD-800 are high impedance headphones. High impedance headphones are generally headphones with low sensitivity. On the one hand, high-impedance headphones are a relatively light load for an amplifier, and most often with such a load the amplifier has minimal distortion. Basically, the problem lies in the maximum voltage that the amplifier is capable of delivering without clipping. There were no problems with the HD-800, no distortion occurred at volumes above a comfortable level, and the listener’s ears were overloaded much earlier. Thus, the emphasis in the advertising booklet on a good volume headroom for high-impedance headphones is correct. But is the amplifier good enough for the HD-800 in terms of quality? Here, to unlock further potential, a separate amplifier would not hurt, but one that would be close to the cost of the HD-800 itself, or a “flavored” one, like a tube amplifier with a compression tint.
Asus Essence One and Audez'e LCD-2
Audez'e LCD-2, like the HE-500, is also isodynamic. Good bass control, there is a headroom in volume. There was no feeling that the amplifier was a bottleneck, the only thing was that due to the mid-range features of the LCD-2, a tube amplifier would probably be more justified for them. In direct comparison with the LCD-3, the older model, the LCD-2's mids are a little harsher, and a softer amplifier would be able to mask this. However, when using a tube amp, you can expect some loss of bass control. As with the HD-800, it feels like a separate amplifier would be in order to further unlock its potential.
Asus Essence One and Audez'e LCD-3
LCD-3 is the flagship of Audez'e. The use of Lotus technology has improved the transmission of the mid-frequency range. In general, the result is the same as with the LCD-2, but without the feeling that the combination would have been better with another amplifier from the tube family. Good bass control, no obvious distortion. Sufficient volume reserve. Considering the cost of the LCD-3, the owner will probably look towards a separate amplifier, but at the same time he will feel quite normal with the one available in the One.
E-MU1616m vs Asus One vs SPL Auditor
Everything is learned by comparison, and as a reference close to the standard of headphone amplifiers, the SPL Auditor studio amplifier from the upper price category (above $1000) was chosen. The best representatives were chosen as headphones: from high-impedance ones - HD-800, from low-impedance ones - LCD-3.
A double-blind test showed that the differences between the devices were easily discernible. The E-MU1616m and One were surprisingly close, with the main difference being the One's tighter sound. The Auditor differs to a greater extent, demonstrating a more natural sound presentation, expressed in better panorama. At some point, a suspicion crept in that Auditor had a scene-forming algorithm built into it, similar to those regulated in Phonitor, but technical tests showed a complete absence of any interference in the signal.
In terms of volume, the One exceeds 1616m with both low-impedance and high-impedance headphones. The One had slightly less distortion with the HD-800, and parity with the low-impedance ones.
Measurements
When measured using the E-MU1616m, it was possible to obtain about 117.9 dB when levels were equalized. Without equalization of levels, the signal level of One is lower and therefore the standard measurement reports show a value of 113-115 dB.
This is practically the limit of the E-MU1616m's capabilities, and indicates that the device does come close to or delivers the claimed 120dB when measured on more accurate Audio Precision equipment.
The distortion of the device is at a very low level, about 0.0004%. When running the One with USB, you can see a skirt around the pitch, which indicates low-frequency jitter. The low noise floor makes it look more intimidating than it actually is.
Upsampling
One of the features of Essence One is the use of upsampling. Typically, upsampling is done in a separate block in the DAC chip and for frequencies of 44 and 48 kHz it is eightfold (for 88 and 96 kHz - fourfold and for 174 and 192 kHz - twofold). The main task of the block is to generate intermediate coordinates for constructing a sound wave, and if without this block the wave represents “steps,” then after upsampling the frequency increases and the steps become smaller. And with small steps, the wave itself is smoother.
The DAC block is not always perfect, and therefore an intermediate solution is to use an external microcircuit. The SRC chip receives a flow of 44 or 48 kHz, and from it 172 or 192 kHz is sent to the DAC itself (which, in turn, often only doubles the frequency with its block).
Since the PCM1795 is capable of receiving 352 and 384 kHz, Asus supplied a resampler capable of delivering exactly these frequencies, and emphasized this advantage against those devices that only upsample up to 192 kHz. The second advantage Asus emphasizes is that frequencies that are multiples of 44.1 are also increased by multiples of 352 kHz (while Dr.Dac Prime 44.1 does not convert to multiples of 192 kHz). Non-multiple recounts often threaten greater distortions than multiple recounts.
Since modern DACs have long ceased to build waves in steps, but rather smooth them out significantly, the quality of upsampling can only be assessed indirectly, by looking at the frequency response graph, the level of distortion and the external shape of the square wave through an oscilloscope.
When the upsampler is activated, one can observe an early rolloff in the high-frequency region, which apparently is the price to pay for the fight against aliasing. This blockage is also clearly displayed on the meander in the form of a decline, the shape of which was recorded using an oscilloscope.
You can observe how the wave front is slightly smoothed out and has a larger angle in deviation from the vertical, and the number of attenuation periods is reduced. In these devices, the frequency response, the type of meander and the distortion spectrum are interrelated parameters, and improving one of them sometimes does not have the best effect on the others.
The distortion spectrum with upsampling looks worse than without it, but this is the price for a different type of impulse response.
If we consider multiple harmonics, then upsampling shows the best results, the second and third harmonics are comparable in level, and the fourth and seventh went beyond the noise level from −135 and 134 dB, respectively, to a level below −145 dB, and the fifth from −123 dB to −130 dB.
The result is clouded by the presence of non-multiple harmonics with a step of approximately 600-700 Hz above the fundamental tone. Here is a reason to think about what is better - reduced multiple harmonics or additional non-multiple ones. However, the resulting distortion level in both cases is 0.0004%.
Test report in RightMark Audio Analyzer
General results
| Frequency response unevenness (in the range 40 Hz - 15 kHz), dB |
IntroductionNowadays, when the sound adapter is built into every motherboard, not many manufacturers dare to release discrete sound solutions. Many companies have completely left the market, others have stopped development and frozen work on drivers, so the appearance of any new device today is of keen and genuine interest to the computer and music community. And if a new brand is introduced to the market, it is tantamount to a sensation. The fact is that the sound card must be very seriously superior to the built-in sound of motherboards in some way, otherwise there is simply no point in buying it. Considering Creative's almost complete monopoly on gaming technologies, almost the only argument in favor of a sound card is the quality of music playback, or rather, even the price-quality ratio, because the use of expensive components and careful design of the printed circuit board will unjustifiably increase the price of the product, and cheap components will not provide of proper quality. The price will also include considerable costs for developing drivers and regularly correcting errors found in them. Having weighed all the pros and cons, most manufacturers chose no longer to deal with such an inconvenient product as non-professional sound cards, but a holy place, as we know, is never empty. The young and daring company Auzentech loudly announced itself in 2006 with the release of several interesting products based on C-Media controllers, and with X-Fi Prelude 7.1 it became known literally in all corners of the world. But last year, 2007, an even more serious player appeared on the sound card market - the world-famous computer equipment manufacturer ASUSTeK Computer Inc. began selling an ambitious audio solution for PCI and PCI-Express peripheral buses.
Formally, ASUS cannot be called a newcomer in the field of sound for personal computers, since in the last century it already released a sound card for the PCI bus - ASUS 3DexPlorer AXP-201. Even earlier, you can recall an audio-video combiner for a specific PCI/ISA slot, which was soldered on some motherboards from the company, for example, ASUS T2P4. About ten years have passed since then, and the company is making a second attempt to conquer the sound card market. Taking into account previous experience, ASUS relied on the extensive capabilities of the product coupled with the highest technical characteristics, and also chose a strategic partner who helped to quickly and competently complete the task. For the Taiwanese company C-Media Electronics, a partnership with such a large manufacturer as ASUS is undoubtedly a good springboard for further growth, so cooperation can be considered mutually beneficial.
In January 2006, at an exhibition in Las Vegas, C-Media presented many interesting new products, two of which are directly related to the hero of today's review. This is a sound controller for the PCI bus C-Media Oxygen HD, which is not inferior in its capabilities to the very common VIA Envy 24HT, and the digital audio processing software package C-Media Hydrogen, which provides support for DirectSound3D, licensed technologies from Dolby Laboratories, as well as many other functions, to We will return to a description of these later as we review the ASUS sound card. The combination of these two new products - oxygen and hydrogen - gave birth to many sound cards from hitherto little-known companies: Bluegears, Sondigo, HT Omega, the already mentioned Auzentech and even Razer. ASUSTeK couldn't stay away either.
Let's look at the characteristics of C-Media Oxygen HD in comparison with VIA Envy 24HT.
Both chips have programmable remapping of output channels and digital monitoring of inputs. One of the Envy24HT's five dual-channel I²S outputs, assigned to the digital output, has a built-in transmitter, but still allows the connection of an additional I²S device. Oxygen HD does not have this feature, but it also has a built-in S/PDIF receiver, the signal from which can be sent directly to the digital output, which allows you to use the sound card as an adapter from an optical cable to a coaxial cable and vice versa. The Envy24HT allows simultaneous recording of only two stereo sources (typically A/D converter and S/PDIF), while the Oxygen HD allows simultaneous recording of three sources (one of which is eight-channel), and the sources can be extremely flexibly selected from four I²S input pairs, built-in digital input and two AC'97 codecs at once.
Functional diagram of C-Media Oxygen HD
Judging by the description, this chip has no noticeable weaknesses and can become the basis for a professional sound card, but today we will look at a product aimed at home use in a media center or gaming computer.
Appearance
The ASUS sound card package is quite rich. In addition to installation instructions, it includes four analog cables “3.5 mm → 2xRCA” 1.8 meters long, a thin one and a half meter optical cable, an additional bracket with a MIDI interface and a bunch of CDs: installation disk, application software, demo Dolby Laboratories disc.
The card itself is strikingly different from other members of its family in that it is covered with a blued aluminum shell, thanks to which it looks and feels like a very serious device. Due to the round cutout in the “armor”, it looks more like a video card than a sound device.
However, the panel with connectors on the ASUS Xonar D2 is completely typical, identically repeating that of the Auzen X-Fi Prelude 7.1: six 3.5 mm connectors (microphone input, line input, four stereo outputs) and two RCA connectors (digital input and digital output).
The combined digital ports are also reminiscent of Auzentech, allowing the connection of both coaxial and optical cables through special adapters inserted into the RCA socket.
However, even here, ASUS engineers found a way to distinguish themselves - multi-colored LEDs are installed inside all six connectors, vaguely reminiscent of color coding of connections, prescribed by instructions PC 99, page 60.
This elegant solution, in addition to purely aesthetic functions, simplifies the process of connecting wires to the sound card. You can determine the right connector by the disappearance of one of the color spots on the wall behind the computer or even on your own hand. By the way, the bundled cables also have an unobvious advantage - the small diameter of the plastic part of the connectors, which allows you to connect a multi-channel speaker system to the card without complications.
The printed circuit board also has CD IN, AUX IN and MIDI I/O sockets. The first two can be connected to low-quality sound sources, for example, a TV tuner - the signal from them goes to the recording mixer, but it can also be sent to the outputs of the sound card by activating the corresponding Monitoring button in Xonar Audio Center. An additional strip with a mini-DIN connector is connected to MIDI I/O, and large DIN connectors MIDI In and MIDI Out are “obtained” using a Y-shaped adapter.
Device
You can learn something about the filling hidden under the protective casing from the manufacturer's description.
ASUS AV200 High-Definition Sound Processor (max. 192 kHz / 24 bits)
24-bit Burr-Brown PCM1796*4 DAC (123 dB SNR, max. 192 kHz / 24 bits)
24-bit ADC Cirrus Logic CS5381*1 (120 dB SNR, max. 192 kHz / 24 bits)
The rest is revealed to the eye if you remove the casing: original rectangles of film capacitors (which we have not yet seen on any high-volume sound card) in DAC filters, solid-state electrolytic capacitors, a scattering of miniature electromagnetic relays (even more of them than in the Creative X- Fi Elite Pro), on the right edge of the board, as well as a myriad of op-amps.
Because the D/A converters used on the card (like most high-end ICs of this type) have balanced current outputs, current-to-voltage conversion is required before the low-pass filter, and this triples the number of op-amps needed.
On three of the four output channels, cheap two-channel amplifiers model 4580 from Texas Instruments are used for the converter and filter, and the much more expensive NJM2114 (in the I/U conversion stage) and LM4562 (in the high-pass filter) are used on the front output. Additionally, the front output uses two RC4580s as a buffer to connect headphones directly to the sound card. A similar circuit design is used at the headphone output of M-Audio Revolution 5.1 and Audiotrak Prodigy HD2 sound cards.
The analog-to-digital conversion filters are made on the NJM5532, but the RC4580 is again used as an inverter for the balanced inputs of the DAC. Such a variety of operational amplifiers may indicate careful work to optimize the quality and cost of the sound card, let's see how all these chips differ.
All four models are recommended by manufacturers for use in audio devices, and three of them have fairly similar characteristics. They are united by very good immunity to differences in supply voltage and ground, and a low level of harmonics in the audio range. However, the LM4562 stands out from this group in terms of speed and distortion, and therefore the logic of the card designers raises certain questions.
You can read about the advantages of the LM4562 over other operational amplifiers, including the NJM2114 using the Creative X-Fi Elite Pro as an example in our previous article. Operational amplifiers for I/U conversion are used in inverting connection, which means LM4562 would work well and in this cascade. Since it has a much larger gain bandwidth and introduces less distortion, it looks strange when combined with the NJM2114. In addition, the output buffer on the RC4580 improves performance with headphones, but when working with a high-impedance load, it practically eliminates all the advantages of the LM4562. Moreover, film capacitors in the feedback circuit of the filtering units are adjacent to ceramic ones in the feedback circuit of the I/U conversion stage. One gets the feeling that individual blocks of the analog part were designed by different engineers who did not consult with each other...
Let's take a closer look at the converters used in the ASUS Xonar D2. Burr-Brown PCM1796 belongs to the Advanced Segment DAC class and, according to the manufacturer, combines excellent dynamics with low sensitivity to jitter. The dynamic range of the converter reaches 123 dB, nonlinear distortion under normal conditions is at the level of 0.0005% for sampling frequencies of 44.4, 48 and 96 kHz, but increases slightly at 192 kHz. The graphs below were obtained using a typical DAC connection circuit. The I/U conversion and filtering stages of the typical circuit use NE5534 op-amps, which do not have outstanding distortion characteristics, so even better results can be expected in other implementations.
However, in the range of digital-to-analog converters manufactured by Texas Instruments there is an even higher-quality model PCM1792A, providing a dynamic range of 127 dB and a distortion level of less than 0.0004% for sampling frequencies of 44 and 48 kHz.
What is noteworthy is that this model is fully compatible with PCM1796 in terms of contacts and command system. If it were not for the four times higher price, it could easily be used in the ASUS Xonar D2 without modifying the printed circuit board. Frankly, I don't see much point in making all four outputs of a sound card the same quality, and ASUS engineers clearly share the same opinion, since they use cheap op-amps on all outputs except the front one. Adhering to the principle of reasonable sufficiency, on the rear channels it was possible to use the PCM1791A (dynamic range 113 dB, distortion 0.001%), which not only costs 30% less than the PCM1796, but also does not require an I/U conversion stage, which will save six operational amplifiers and even more strapping parts. There is an even more radical option that allows you to create a low-profile version of the card - the six-channel PCM1602A (dynamic range 105 dB, distortion 0.002%), providing three stereo outputs at once at a price less than one PCM1796. By the way, the recently released low-profile Xonar DX card is built according to exactly this ideology: a high-quality two-channel DAC Cirrus Logic CS4398 (as on the Creative X-Fi Elite Pro) for front output and a six-channel Cirrus Logic CS4362A (dynamic range 114 dB, distortion 0.001%) for three remaining exits.
The ASUS Xonar D2 analog-to-digital converter, on the contrary, is based on the best Cirrus Logic model - CS5381, providing a signal-to-noise ratio of 120 dB and distortion of 0.0003% at any sampling frequency, including 192 kHz.
Perhaps this is the highest quality of the mass-produced analog-to-digital converters. Theoretically, it can be used to carry out the most accurate measurements of signals in the frequency range of about 50 kHz (above this, signal suppression by a digital filter begins, even at a sampling frequency of 192 kHz), but there is one “but” - the analog part must correspond to the same highest level. The manufacturer itself recommends implementing a low-pass filter on ultra-low-noise operational amplifiers LT1128 from Linear Technology, which have minimal offset voltage and excellent distortion (about -130 dB), but ASUS engineers used not so high-quality NJM5532.
Driver Features
The ASUS Xonar D2 driver differs from the basic driver for C-Media Oxygen HD in OpenAL support, SVN and DS3D GX functions, as well as a different control panel, stylized as a pocket media player, with the characteristic name Xonar D2 Audio Center. In the latest drivers, the panel is completely Russified, which may be important for many Russian buyers.After installing the driver, the panel reveals a minimum of controls - a few buttons and a volume control, and the rest of the space is occupied by a huge information display with an indication of the current settings and a primitive spectrum analyzer.
It is primitive because the accuracy of its testimony does not stand up to criticism. The round volume control looks beautiful, but is not very easy to use - you can’t turn it with any movement of the mouse, and it doesn’t respond at all to turning the mouse wheel.
You can view the versions of software components and some other information in the window called up by the button with the letter “i”.
The “SVN” button next to the volume control activates the volume normalization mode, a function that has proven to be very useful when watching films with quiet speech but loud special effects. In games, it is better not to enable automatic volume change, because it blurs the sharpness of shots and explosions, seriously worsening the auditory experience.
A group of five buttons in the lower right corner of the audio center includes the DS3D GX function and one of three audio processing options - games, movies, music. HF, on the other hand, disables all processing; It was in this mode that I measured and assessed the sound in music. The remaining controls are hidden under the information display “cover” that slides up.
Here you can find the choice of the card's reference frequency, the choice of the number of speakers, the choice of digital output data format, as well as the settings for Dolby licensed technologies. For example, for headphones, any of them includes Dolby Headphone, and for stereo speakers - Dolby Pro Logic IIx and Dolby Virtual Speaker in one of two operating modes.
Many other options are displayed by clicking the correspondingly named buttons. Why was it necessary to hide all this wealth under a very slowly sliding lid? Thank God that you only need to wait for it to move once, and then the selected position is remembered in the registry.
As you can see, the available set of settings depends on the selected speaker system configuration. For some reason, two speakers are missing DPL IIx and DTS settings, with Pro Logic turning on automatically when Dolby Virtual Speaker is activated. With headphones, Virtual Speaker Shifter is enabled only after Dolby Headphone is activated.
In the basic C-Media drivers, Virtual Speaker Shifter operates independently of Dolby Headphone, allowing you to activate technologies for converting stereo sound into multi-channel, from which we can conclude that Virtual Speaker Shifter should create a virtual 7.1 system and then mix the sound into the required number of channels. Nothing like this is observed in the latest drivers, which means you can suspect a banal error in the driver or its control panel.
The position of the speaker on the virtual room plan determines the volume of the corresponding playback channel, and if, for example, you move the right speaker to the left, then both channels will be mixed into the left “ear”. This setting can be considered as a simplified alternative to Creative THX Console with significantly less functionality. THX Console allows you to set the distance in meters and direction in degrees for each speaker of the speaker system, based on which the volume of the corresponding channel and signal delay are adjusted. ASUS's implementation is not tied to any units of measurement at all - apparently, the user needs to select the position of the speakers by ear. Then why is there no test signal for this?
By comparison, the basic C-Media drivers at least display relative volume in decibels, allow you to set delays for the center and rear channels, and also offer three test signals to evaluate the result. By the way, if you install the ASUS driver manually, and not through the Setup.exe executable file, then you will be able to see the original C-Media control panel.
ASUS's digital output settings also differ from the base driver, but this time for the better. The output format and clock frequency are separately set, which is valid for the entire card (including DAC/ADC) and is observed when the digital output is disabled. The C-Media control panel allows you to select the base frequency only when S/PDIF is enabled.
S/PDIF on the ASUS Xonar D2 can transmit uncompressed stereo with a sampling frequency from 44.1 to 192 kHz, 5.1 audio in Dolby Digital Live or DTS Interactive formats, and also transmit the signal from the digital input without processing. The last option allows you to use the card as an adapter from coaxial to optical cable and vice versa. When DDL or DTS encoding is enabled, the card is switched to 5.1 mode and the analog outputs are disabled. The volume control continues to work and it is possible to enable automatic SVN adjustment.
Dolby Pro Logic IIx in this case is responsible for decomposing the stereo into 5 speakers, although with headphones or a two-channel speaker system, this technology can also perform the opposite function, mixing multi-channel sound into stereo. DPL IIx supports seven-channel speaker systems and has three operating modes, of which only “Music” and “Movie” are available in ASUS Xonar, and for some reason there is no “Game” mode. In Music mode, you can adjust the balance of mid frequencies (vocals) between the center and two front speakers, as well as the depth of the sound field. The “Panorama” option present in the original C-Media control panel is also lost somewhere.
To decompose stereo into a multi-channel configuration, you can also use the alternative DTS Neo:PC technology, which has completely similar operating mode settings.
But how long can you study one section of settings? Although he is the main one, he is far from the only one. Next in order is the “Mixer” section.
As with many other sound cards, the playback mixer is separate from the recording mixer, which makes pressing an extra button when you need to change recording parameters. In the original C-Media control panel, playback and recording settings are on the same page, which is much more convenient. But, most importantly, the Xonar D2 Audio Center does not have a single level indicator (the so-called peak meter), although a couple of indicators are present even in the C-Media panel. An example to follow here is the Audiotrak Prodigy 7.1 control panel, where each volume control is equipped with a signal level indicator column.
In addition to the usual Wave, MIDI and CD volume controls, the playback settings allow you to separately set the volume of each of the analog outputs, and by default they are set to far from the maximum volume.
The recording mixer allows you to select one of many signal sources for recording: the familiar “SPDIF In”, “Line In”, “CD In”, “Aux” and “Mic”, the less common “Wave” and “Mix”, as well as a unique "Alt". If “Wave” is a digital loop-back, allowing you to record the reproduced signal with bit precision, then “Alt” is a bridge between the linear output and the linear input of the card. This recording source can be useful when playing protected content for which the license agreement requires all digital recording sources to be disabled. I haven’t had the chance to test this thesis in practice, but you can find other useful applications for “Alt,” for example, the manufacturer recommends making measurements in RightMark Audio Analyzer using it.
“Mix,” as you might guess from the name, combines signals from all sources. This is a laudable feature, but the feature would be doubly useful if the user were given the choice of which sources to mix and which to ignore. It is also somewhat inconvenient that the nominal recording level is obtained at the maximum position of the level control. To increase the volume of a quiet signal, you will have to use some kind of sound editor. Because of this, in particular, I was unable to carry out full measurements of the card with headphones connected: the volume with a low-impedance load dropped by more than 10 dB and RightMark could no longer cope with level normalization, and using a Creative sound card for recording led to not entirely adequate results.
Enough about the shortcomings, the ASUS Xonar D2 recording mixer also has a very convenient thing - monitoring of all inputs. Buttons with the image of an eye allow you to play a signal from the corresponding input for auditory control, and any number of these buttons can be pressed simultaneously. Now, if only the “input selector” worked according to this principle...
However, I got carried away again. Let's see what opportunities are hidden on other pages of the improvised menu.
On the tab called “Effect” we see tacky settings for the ambient effect (reverb) and equalizer. The logic of the creators, who put four options for acoustic environments on buttons, and left the rest in a drop-down list, the selected value of which will be activated when the fifth button is pressed, makes me feel slightly bewildered. In addition, the lack of adjustment of the reverberation intensity is sad. Let's say I would like more echo in games, but I have to make do with what they give.
The equalizer is a separate story. Not only is it tiny, and it’s almost impossible to set the necessary parameters with its help, but it also works somehow strangely. Having tried to slightly muffle the 4 kHz band, I did not notice any changes in the sound, and when I moved the slider to the very bottom, I realized that 4 kHz had been cut out completely. The funniest thing was that it was possible to bring this frequency back to life only by resetting the settings with the “Default” button. Saving custom equalizer settings is also not intuitive. To do this, you need to type the name of your setting in the lower input field and press the button with the “plus” sign, and delete the saved setting using the “minus” button.
In my humble opinion, the equalizer was worthy of a separate menu tab, especially considering the lack of tone controls that are familiar to most users.
On the tab called “Karaoke” there are three settings available: the tempo of the music, the suppression of the voice in the song and the echo effect for the microphone. The meaning of these settings is clear to anyone who has ever sung karaoke, so let’s move on to the next, very interesting menu item called “FlexBass”.
Here, in full accordance with the name, the distribution of bass between the speakers is flexibly adjusted. The crossover slider determines the limit below which frequencies are sent to the subwoofer and cut from those channels that are set to small. For large speakers there is no low frequency cut.
The crossover works very well, providing a symmetrical roll-off of 36 dB per octave and without introducing any distortion into the sound.
The two bottom buttons, "AEC" and "VocalFX", appeared in the drivers quite recently.
The “AEC” mode, or “Acoustic Echo Cancellation”, is intended for video conferencing and other important conversations over the Internet, therefore it turns off all processing effects and tries to suppress sounds penetrating into the microphone from the speakers. A quick test of this mode showed high suppression efficiency.
In my opinion, it would be more convenient to activate AEC using the button in the lower right corner of the Xonar D2 Audio Center (where preset audio processing options are grouped), since the entire setting is essentially represented by a single “On/Off” checkbox.
The last tab, previously called "Magic Voice", contains several additional functions for processing the signal from the microphone. These include changing the voice timbre (male, female, “cartoon” and monster voice), applying one of four environmental effect options, as well as a special effect for games.
VoiceEX applies the reverb to the player's voice that is specified by the game for their current location. This feature was first introduced by Creative Labs as part of EAX 5, and now ASUS can proudly say that its product supports the latest technologies of its competitor. We will find out whether this is actually true a little later, when we test the card in games, but for now we will look at other parts of the driver that are hidden from view. For example, ASIO support.
ASIO is a special interface for transmitting data to a sound card with a specified delay and is used in the vast majority of sound processing programs. ASUS Xonar D2 provides full ASIO 2.0 support with 16- or 24-bit data precision and frequencies of 44.1, 48, 96 and 192 kHz. In addition, the driver supports such a wonderful feature as ASIO multi-host, thanks to which several programs can simultaneously work with ASIO. There is no frequency automatic on the card, so a signal with a sampling frequency different from the base one is recalculated by a high-quality software resampling algorithm. For comparison, Creative X-Fi in this case begins to methodically switch the frequency of the generator, accompanying this process with the incessant clicking of the relay.
The implementation of ASIO in ASUS Xonar could be called exemplary if it provided parallel recording of more than one source, as well as several additional playback channels, of which the Creative X-Fi, for example, has as many as 18. Let me remind you that the C-Media Oxygen HD audio controller used on the ASUS Xonar D2 allows simultaneous recording of eight streams. It would also be nice to be able to call up the ASIO settings window from somewhere in the Xonar D2 Audio Center.
Oh yes, I completely forgot to tell you about another original function of this sound card. After installing the driver, you will find two audio devices on the system, ASUS Xonar D2 Audio and ASUS Xonar D2 Converter. The latter device is designed for quickly applying effects to music recordings. If you use an MP3 player and like the spatial effect created by Dolby Headphone or Virtual Speaker technologies, or simply want to adjust the sound of your recording with an equalizer, using the bundled ASUS Portable Music Processor program you can transcode your favorite songs into mp3 or WMA formats with any available special effect driver.
On this note, I propose to finish studying the potential capabilities of the card and move on to more relevant field tests.
Listening to music
ASUS Xonar D2, as a very high-end sound card, was compared with the best non-professional models to date - Creative X-Fi Elite Pro and Auzen X-Fi Prelude 7.1. To evaluate the sound quality of sound cards, we used Grado SR 325i headphones coupled with a C.E.C. amplifier. HD53R Ver. 8.0, connected to the sound card with a Monster Standard Interlink 200 cable, recordings of various genres saved from CDs in wave format, as well as foobar2000 0.9.5 and WinAMP 2.95 players. The sound cards were set to the same volume - standard 2 V RMS - to get maximum dynamic range. In the foobar settings, replay gain was disabled, the sound was output via DirectSound in 32-bit format. WinAMP was used in conjunction with the plugin ASIO output (dll version) 0.67 SSE2.The reason for such a detailed description of versions and settings is trivial. Even when writing the review of Auzen X-Fi Prelude 7.1, I noticed that not every player or audio output plug-in provides the correct transmission of reverberations and localization of sounds in space, and these two options are relatively reliable. For such high-quality sound cards, choosing the right software player is of considerable importance. For example, the ASIO audio output plugin for Foobar version 0.9 does not sound correct, and this is easily confirmed by measurements.
Graph of intermodulation distortion when outputting sound via ASIO in different ways
players. Digital loop, 44.1 kHz 16 bit
The first experience of listening to music on the ASUS Xonar D2 with the included drivers did not leave the most favorable impression. Her generally very clear and detailed sound lacked depth and richness of overtones. Using additional epithets, I will call this sound faded, faded. In addition, the sound stage turned out to be wide, but absolutely flat, without separation, which completely took away the pleasure of listening. Fortunately, the programmers found the bug, and things have gone much better with the current drivers - so don't neglect updating them.
The card instantly captivates with its deep and dynamic sound. I was very impressed by the confident transmission of the smallest details against a loud background, which is especially noticeable in the richness of the sound of the violins, including in a large orchestra. The timbres of other musical instruments are also quite natural, the mids and highs are clear and detailed, the bass is clear and rich. But, despite all these advantages, there is not always enough “air” in the sound; after-sounds and natural reverberations are quickly lost in the total mass, which is why, with many simultaneously sounding instruments, a feeling of lack of detail arises. This is clearly audible in comparison with Auzen X-Fi Prelude. How delicately she treats room acoustics! Spaciousness, realistic volume even on the bass, excellent detail and microdynamics in the upper register, giving high naturalness of timbres, make Prelude the best choice for jazz music and other “live” recordings. Xonar differs from Prelude in harsher high frequencies, but noticeably better macrodynamics, which clearly decided the debate in favor of Xonar on Judas Priest records.
The sound of the Creative X-Fi Elite Pro initially amazes with its energy and emphasized detail, but the elastic, well-developed bass is adjacent to caustic high frequencies, and the mids are inexpressive and overtly colored - after the ASUS Xonar D2, it seems that most instruments play a semitone higher. When mixed, the colors from several instruments lead to a deterioration in spatial resolution, while reflections of high-frequency sounds from the studio walls (reverberation) lose their isolation and form something difficult to recognize with the original sound. I have already encountered something similar, namely an unpleasant-to-hear harshness and aggressiveness, on the good old Audiotrak Prodigy 7.1, which still remains on my computer thanks to one accidental discovery.
While studying the documentation for the Wolfson WM8770 digital-to-analog converter, I noticed how much the digital filter characteristics differed at different sampling rates, and tried software resampling (SSRC) of recordings at a frequency of 192 kHz, and then at 176.4 kHz - a frequency that is a multiple of standard for music is 44.1 kHz. The result pleased me very much: the sharpness disappeared, the stage became much more voluminous, and with such sound, the desire to buy an even more expensive sound card disappeared. Much later, when I decided to replace the operational amplifiers, an interesting detail became clear - with operational amplifier models that are faster than the standard NJM4580, oversampling does not provide any improvement! The front output of the Creative X-Fi Elite Pro uses NJM2114 op-amps that are close enough in performance to the NJM4580 that I decided to try software resampling again.
Creative sound cards from the X-Fi family do not support higher sampling rates in Audio Creation mode, so we had to limit ourselves to 96 kHz, but this was enough to significantly improve the situation. The coloration becomes much less and the high-frequency “patina” almost completely disappears from the scene, and the mid-range frequencies are much better developed. First, I used resampling in the ASIO audio output plugin for WinAMP, then I simply set the desired clock generator frequency in the Creative mixer settings, using the card’s hardware capabilities for resampling - the result was the same. By switching the sound card to the “Entertainment” mode, where stereo recordings are always converted to 192 kHz, with the equalizer, Crystalizer, CMSS and SVE turned off, I got even cleaner and richer sound at the cost of a very slight loss of spatial clarity. Thus, owners of Creative X-Fi who do not want to deal with resoldering chips on their sound card can be advised to stay in “Entertainment” mode when listening to music. X-Fi's hardware conversion to another digitizing frequency is implemented very well, and the resulting sound is better than with honest bit-for-bit reproduction at a clock generator frequency of 44.1 kHz.
However, in a previous review, I noted that Auzen X-Fi Prelude 7.1 exhibits different behavior, namely a drop in clarity without noticeable improvements in other characteristics.
What about Xonar, does oversampling give it anything, since both the NJM2114 and RC4580 are involved in the front output? To begin with, I simply clicked the frequency selection setting in ASUS Audio Center, but I could not hear any obvious differences in the sound - in some places there was no difference at all, on vocals sometimes it seemed that the sound became dirtier. Then the same WinAMP with a plug-in for audio output via ASIO was put into use, and doubts immediately disappeared: recalculation to 192 kHz with “Ultra” quality gives space, the lack of which I noted above, makes the high frequencies softer and more detailed, and also adds a little more dynamics. The differences are less noticeable than on the Creative X-Fi Elite Pro, but still enough to be taken into account.
A signal with 16-bit accuracy and a sampling frequency of 44.1 kHz is transmitted without distortion through any interface available to the card. The results for ASIO, which slightly exceed the theoretical capabilities of the format, are the result of an error in the Rightmark Audio Analyzer playback procedure, since when played through WinAMP with the ASIO plug-in, a complete match with the reference signal is obtained.
A test signal of 24-bit precision, at first glance, all interfaces transmitted without loss, however, a detailed study of the noise floor in the presence of a tone with a high level showed that the Kernel Streaming interface was closest to the original, although DirectSound with MME are practically no different from it . But this time ASIO added a small amount of distortion, which is not present when playing the signal using WinAMP.
Even the prehistoric Wave Out in the latest versions of ASUS Xonar drivers copes with signal transmission with 32-bit precision, and DirectSound even managed to slightly exceed the theoretical dynamic range limit. However, the measured level of noise and interpenetration of channels clearly indicates that the driver performs some kind of rounding beyond the 24-bit accuracy of signal representation. This may be a consequence of converting the signal to floating point for the volume controls and resampling algorithm.
The ASIO result is completely similar to what was obtained with 24-bit precision, from which we can make an assumption about the nature of the error in working with ASIO in Rightmark Audio Analyzer. The fact is that C-Media allows two ASIO options, with 16- and 24-bit signal precision, while the implementations of all other manufacturers adhere to the more CPU-friendly values of 16 and 32 bits. Apparently, this development of events was not foreseen by the developers of the test package.
Interestingly, in this case, Kernel Streaming turned out to be somewhat worse than the standard interface. The picture below shows the spectrum of the recorded signal in the dynamic range test, which most clearly illustrates the behavior of the driver.
Dynamic range test spectrogram
Now let's move on to measuring the quality of the analog part of sound cards. The first step is to determine which card has a better linear input, for which it is necessary to measure the linear outputs through its own linear input and the input of another card.
The line inputs of the ASUS Xonar and the X-Fi Elite Pro turned out to be almost identical in quality, with a minimal advantage of the ASUS Xonar D2 in terms of noise, if you do not take into account the fact that for the Creative X-Fi it was necessary to select a PCI slot with the lowest power supply noise (it turned out to be the lowest slot of the motherboard), and ASUS Xonar D2 showed equally good results in any slot.
Since connecting one card to another leads to deterioration in measurement results, further research will be carried out through each sound card's own line input. First, let's study the parameters of the front and rear channels of the two cards. Let me remind you that they differ only in the operational amplifier models.
Judging by the data obtained, the front output of the ASUS Xonar D2 differs from the front output of the Creative X-Fi Elite Pro only in terms of nonlinear distortion. The situation is absolutely the same with rear exits. Of course, based on the stingy numbers, the ASUS Xonar D2 turns out to be the winner, but in the Auzen X-Fi Prelude review I already wrote that the best number does not necessarily give the best sound, so let’s compare the levels of individual harmonics.
Xonar D2 Out 1 (Front) Distortion Spectrum
Xonar D2 Out 2 (Rear) Distortion Spectrum
X-Fi Elite Pro Out 1 (Front) Distortion Spectrum
X-Fi Elite Pro Out 2 (Rear) Distortion Spectrum
The front output of the ASUS Xonar D2 showed a significant difference between the channels. In the left channel, the harmonic level is generally lower by about 10 dB, but in the right channel the fifth harmonic is completely absent. I don’t presume to judge the reasons for this behavior, I will only say that the rear output did not demonstrate anything like this, but was greatly inferior to even the worst of the two front output channels. The line output of the Creative X-Fi Elite Pro lost just as much in terms of the third and fifth harmonics, and its seventh harmonic is more than 10 dB higher. As a result, the ASUS Xonar D2 wins the competition of “main” outputs by a wide margin, but the rear channels of the Creative sound card look much more convincing.
Now let's check how the measured characteristics of the two cards change depending on the signal sampling frequency.
Xonar D2
X-Fi Elite Pro
Creative X-Fi does not allow recording a signal with a frequency of 192 kHz, so measurements were not carried out in this mode, however, it is noticeable that its behavior is noticeably different from the ASUS Xonar D2 - the best results in terms of noise and dynamic range were obtained at a frequency of 96 kHz. In addition, ASUS was significantly inferior in these parameters at a frequency of 44 kHz. What is this, a problem with playback or recording of the signal? You will have to take measurements again through the linear inputs of another card.
Obviously, the decrease in dynamic range at a sampling frequency of 44 kHz in the ASUS Xonar D2 is not related to the operating features of the analog-to-digital converter, but lies entirely with the conscience of the playback path. Is this the reason for the noticeable improvement in the sound of music when using software resampling? As we found out earlier, the driver completely correctly transmits a digital signal with 24-bit precision, which means that the dog is buried somewhere deeper, perhaps in the interface with the DAC or in the clock generator. I would like to believe that ASUS, together with the employees of C-Media, will be able to sort out this problem in the card’s operation, just as they have already eliminated the intermodulation distortion observed when using earlier versions of drivers for the Xonar D2.
Taking this opportunity, I conducted a similar study at a sampling frequency of 96 kHz.
Comparing the obtained noise figures with previous results, we come to the conclusion that the Creative X-Fi Elite Pro analog-to-digital converter works best at a frequency of 96 kHz, and a similar functional unit of the ASUS Xonar D2, on the contrary, provides the greatest dynamic range at a frequency of 44.1 kHz. If it were not for the annoying problem with playback at this frequency and the smaller spread of distortion between the left and right channels of the front output, the measurement results of the ASUS sound card could have been even more impressive.
Those wishing to familiarize themselves with the full test results in RMAA can download the archive with them (7.7 MB).
Conclusion
After taking a closer look at the ASUS Xonar D2, we can admit that this is one of the most versatile sound cards on the market. The highest quality technical performance allows it to show the best results among mass products in measurements, it sounds great in music, provides excellent surround sound in games and has the most feature-rich driver I have ever seen. The number of different sound effects and useful additions, such as automatic encoding of multi-channel audio into Dolby Digital and DTS formats, will satisfy even the most sophisticated user. Of course, you can complain about the lack of a driver for Linux, however, on the other hand, if the sound card is used in a multimedia computer running Windows Media Center Edition, the ASUS Xonar D2 driver will install a special version of the control panel optimized for display on a TV.Support for MIDI devices, excellent implementation of ASIO 2.0 and excellent quality of digitization of analog inputs make the card suitable for professional use in audio recording. For those who want to try their hand at creating music, the card comes with a set of professional applications with somewhat limited functionality. The only drawback in this regard is the inability to record several sources simultaneously, although the heart of the card - the C-Media Oxygen HD controller - allows this.
Positive aspects also include a licensed Power DVD 7 and a solid set of accessories for connecting the card to an amplifier or receiver. If you are going to use only headphones, then you don’t have to worry about an additional amplifier, since the card copes well even with low-impedance loads. Although for those who have no reason to connect headphones directly to the sound card, an additional stage on not the highest quality operational amplifiers is likely to spoil the mass, since it inevitably degrades the sound quality, but does not relieve the card from being sensitive to interconnect cables. To the credit of ASUS, the supplied cables are of sufficient length and quality; there is little point in looking for something else.
In order not to retell the contents of the entire review, I will not summarize the advantages and disadvantages of the ASUS Xonar D2, especially since the main complaints relate to the Xonar D2 Audio Center control panel. The versatility of the card makes it difficult to unambiguously determine the target audience, but the main strength of the card can be named - the highest quality of all analog outputs. This makes it especially attractive for creating a home media center with very high-end multi-channel acoustics. Household DVD players with comparable quality hardware will cost an order of magnitude more than ASUS asks for its product.
And yet, for complete audiophile happiness, I would like more - a Deluxe version of the card, with an even higher-quality Burr Brown PCM1792 digital-to-analog converter and the highest quality operational amplifiers at the front output.
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