The time has finally come to publish a review of the ASUS audio cards I've been using since June of 2009. Since that time many reviews of these ASUS cards have been published. It's always nice to be one of the first publications to review a product, but not without due diligence. The ASUS Xonar HDAV1.3 Slim and Xonar Essence STX were released with less-than-stellar device drivers causing the cards to resample and change the audio stream before the bits were output to an external DAC. The result was severely diminished sound quality. In recent months ASUS released an updated ASIO driver and software that enables bit transparent digital audio output from both cards at all pertinent sample rates. Over the last month I've spent many hours with the ASUS audio cards. I discovered the updated ASUS ASIO driver and software was not the golden ticket I hoped for all this time. I demonstrated time and again that bit transparency is merely the first step toward the highest quality home audio. More importantly I proved the inexpensive ASUS Xonar HDAV1.3 Slim and Xonar Essence STX audio cards are capable of good (HDAV) and really good (STX) sound.
[PRBREAK][/PRBREAK]
<b>Introduction</b>
Most audiophiles have never heard of ASUS even though most audiophiles have used ASUS products. ASUSTeK is a large computer component manufacturer based in Taiwan. The company has supplied components to Apple, Dell, Hewlett Packard and many others. Over the last two decades ASUS has earned a reputation among computer geeks for manufacturing high quality innovative product such as motherboards and high end graphics cards. Over the last two years ASUS has earned a reputation among computer audiophiles for manufacturing high quality consumer audio cards. In fact ASUS sent a few representatives to the <a href="http://www.computeraudiophile.com/content/Computer-Audiophile-Symposium-Performance-Playback">Computer Audiophile Symposium</a> held at Fantasy Studios to glean as much information about this market as possible. I enjoyed seeing ASUS reps discussing audio cards with the likes of Pflash Pflaumer (<a href="http://www.berkeleyaudiodesign.com/">Berkeley Audio Design</a>) and Keith Johnson (<a href="http://www.spectralaudio.com/">Spectral Audio</a>, <a href="http://www.referencerecordings.com/">Reference Recordings</a>). The knowledge shared that day will hopefully make its way into future ASUS products.
The convergence of computers and high-end audio has opened a new market for high quality consumer grade audio cards. Audiophiles have already rejected lo-fi cards such as the Creative Soundblaster and the Turtle Beach Montego in favor of professional models from Lynx and RME. These professional grade cards offer up to 8, 16, 32, 64 or 128 channels, external word clocking options, unfriendly user interfaces, and high price tags ranging from $600 to over $1,000. Now that ASUS has entered the high quality consumer audio card market the game has changed. ASUSTeK's ability to produce high quality consumer audio cards at very reasonable prices, through economies of scale beyond any small audio company's dreams, amounts to stiff competition for audio card manufacturers and a boon for consumers of high quality audio. ASUS has aimed to make cards such as the Xonar Essence STX perform at a level close to Lynx and RME cards for prices much closer to lo-fi audio cards. Usually mass and class are inversely proportional but ASUS has managed to manufacturer high class products at mass market prices.
The <b>Xonar HDAV1.3 Slim</b> PCI card ($150) is focussed narrowly on the home theater PC (HTPC) market. Most of its capabilities are related to Blu-ray, High-Bandwidth Digital Content Protection (HDCP), and support for 24p video. Astute computer audiophiles have noticed this card is also great for small chassis music servers such as the OrigenAE M10. These small servers usually accept one half-height PCI card only. The Xonar HDAV1.3 Slim fits the bill perfectly as a half-height PCI card with an electrical S/PDIF (coaxial) digital audio output in addition to HDMI in/output. The specifications on the ASUS website simply state this card supports <i>"44.1K/48K/96K/192KHz @ 16/24bit"</i> using the ASIO driver and the digital S/PDIF output. I can verify the ASIO driver supports 88.2 kHz and 176.4 kHz at 24 bit in addition to those rates listed on the ASUS site and all are bit transparent. However, supporting these sample rates is one piece of the playback puzzle and a long way from good sound.
<center><a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav01.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav01-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav05.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav05-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav04.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav04-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav03.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav03-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav06.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav06-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/hdav02.png" class="thickbox" rel="hdav"><img src="http://images.computeraudiophile.com/graphics/2010/1217/hdav02-thumb.png"></a>
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The <b>Xonar Essence STX</b> PCI Express (PCIe) card ($199) is a great match for computer audiophiles. This full size card is more difficult to squeeze into a small music server chassis, but it can be done using a PCIe riser card that aligns the card parallel with the motherboard. ASUS went to great lengths designing this card for such a discerning market. The Xonar Essence STX offers a 124db SNR (Signal-to-Noise Ratio), hyper-grounding circuitry design, EMI shielded analog output, PCM1792A Digital-to-Analog Converter (DAC), Nichicon "Fine Gold" capacitors, and interchangeable OPAmps. More importantly the Xonar Essence STX offers an electrical S/PDIF (coaxial) digital audio output that connects to an external DAC. The onboard DAC is likely very good for what it is but it's no match for external DACs such as my current references the Berkeley Audio Design Alpha DAC and <i>d</i>CS Debussy. According to the ASUS specs this digital output supports <i>"44.1K/48K/96K/192KHz @16/24bit with very low latency"</i> when using the ASIO driver. As with the HDAV card the STX supports 88.2 kHz and 176.4 kHz bit transparent output with the same ASIO driver. The Xonar Essence STX is a much more robust card than the Xonar HDAV1.3 Slim and goes well beyond simply supporting high sample rates with an ASIO driver.
<center><a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-06.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-06-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-01.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-01-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-04.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-04-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-03.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-03-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-02.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-02-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-05.png" class="thickbox" rel="stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/stx/stx-05-thumb.png"></a>
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<b>Discovery</b>
The Xonar HDAV1.3 Slim and Xonar Essence STX were not my favorite audio components during the second half of 2009 and first half of 2010. Outputting bit transparent audio at all sample rates was a serious challenge. I stuck with the ASUS drivers and software only to be disappointed after each update. After many months of sending feedback to ASUS and discussing the audiophile requirements of outputting a perfect audio stream and supporting all pertinent sample rates ASUS came through with what appeared to be a working ASIO update. I thought surely I was done screwing around with drivers and software settings. The ASUS Xonar HDAV1.3 Slim and Xonar Essence STX cards were ready for primetime. I was ready to put these cards through the digital wringer and listen to some music. I soon discovered the newest ASIO driver wasn't a silver bullet. The HDAV card struggled and was frequently unlistenable when using the ASIO driver. The STX functioned just fine using ASIO, but there were better ways to output audio. Fortunately none of this ASIO business really mattered. Output modes such as WASAPI, Kernel Streaming, and the new WASAPI - Event Style led to better results, especially for the Xonar HDAV1.3 Slim.
I consider J River Media Center 15 to be the best consumer audio playback application available on the Windows platform. I used it exclusively during this review. The Xonar HDAV1.3 Slim card was used in the <a href="http://www.computeraudiophile.com/content/Computer-Audiophile-Pocket-Server-CAPS">Computer Audiophile Pocket Server</a>. The C.A.P.S. server is fairly low powered with no moving parts. It holds two gigabytes of memory and runs the Windows 7 Ultimate 32-bit operating system. The Xonar Essence STX card was used in a Mac Pro with two quad-core Intel processors, ten gigabytes of memory, and four one terabyte Hitachi hard drives. The Mac Pro operating system was the Windows 7 Ultimate 64-bit edition. I used a single Kimber Select KS2020 (WBT-0102 Ag) coaxial digital cable with both cards to limit variables.
Many different software configurations were tested with both audio cards. Some configurations worked wonderful while others wouldn't play intelligible music. What follows are working and nonworking configurations with some notes about playback using each method. These configuration options can be located within J River Media Center by selecting Tools > Options… > Audio from the top menu. Readers mirroring these working configurations on their home computers <u>should</u> achieve similar results. Please remember death and taxes are the only guarantees in life.
<b>Windows 7 Control Panel Sound Settings</b> (click to enlarge):
<a href="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-01.png" class="thickbox" rel="win7-settings"><img src="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-01-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-02.png" class="thickbox" rel="win7-settings"><img src="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-02-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-03.png" class="thickbox" rel="win7-settings"><img src="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-03-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-04.png" class="thickbox" rel="win7-settings"><img src="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-04-thumb.png"></a> <a href="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-05.png" class="thickbox" rel="win7-settings"><img src="http://images.computeraudiophile.com/graphics/2010/1217/windows-audio-settings-05-thumb.png"></a>
<p><b>Xonar HDAV1.3 Slim - Working Configurations.</b>
</p>
<p>
<b>One</b> - This was the most responsive and smooth operating configuration. Bit transparent output was verified at all supported sample rates. CPU utilization was 10%-30% with 500 MB of 2 GB of memory in use during regular listening periods.
<ul>
<li>J River Audio Output Mode: WASAPI - Event Style. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-01.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>Device: S/PDIF Pass-through Device (ASUS Xonar HDAV1.3 Slim Audio Device). (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-02.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>Open device for exclusive access: Enabled. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-02.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>Hardware Buffer Size: 100 milliseconds (J River Recommended). (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-02.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>All DSP and Output Format settings disabled (unchecked). (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-03.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>Prebuffering: 2 seconds. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/wasapi-event-style-01.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="hdav-wasapi">graphic</a>)</li>
</ul>
</p>
<p>
<b>Two</b> - For the most part this configuration worked well. Bit transparent output was verified at all supported sample rates. CPU utilization was 10%-30% with 500 MB of 2 GB of memory in use during regular listening periods. When the two options to Flush Device Buffers on Startup and Pause are enabled very audible pops occur when switching tracks.
<ul>
<li>J River Audio Output Mode: WASAPI.</li>
<li>Device: S/PDIF Pass-through Device (ASUS Xonar HDAV1.3 Slim Audio Device).</li>
<li>Open device for exclusive access: Enabled.</li>
<li> WASAPI Buffering: 0.50 seconds (default)</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="hdav13wasapi">graphic</a>)</li></li>
</ul>
</p>
<p>
<b>Three</b> - This configuration worked consistently with one exception. My computer locked up when switching tracks one time causing me to reboot. I emphasize this only happened one time out of many tracks changes. The issue could be totally unrelated to Kernel Streaming and the Xonar HDAV1.3 Slim Device. Bit transparent output was verified at all supported sample rates. CPU utilization was 10%-30% with 500 MB of 2 GB of memory in use during regular listening periods.
<ul>
<li>J River Audio Output Mode: Kernel Streaming.</li>
<li>Device: ASUS Xonar HDAV1.3 Slim Digital.</li>
<li> Kernel Streaming Buffering: 0.50 seconds (default).</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="ks-pcm">graphic</a>)</li></li>
</ul>
</p>
<p><b>Xonar HDAV1.3 Slim - Nonworking Configuration.</b>
</p>
<p>
<b>One</b> - Despite all the work done by ASUS to perfect its ASIO driver I had nothing but problems. Huge stutters and small ticks & pops were common during playback. Mouse movements, large and small, produced easily audible noises. This was not the case with any other configuration. The configuration documented below offered the best performance from this ASIO driver but it was still unacceptable to me. Other unsuccessful configurations I tried involved setting the ASUS ASIO Latency from 10 to 80 ms and ASIO Buffering to 0.10 to 0.44 seconds. Disabling large hardware buffers, setting the ASIO Buffering to 2 seconds (highest) and the ASUS ASIO Latency to 80 (highest) didn't change the poor performance noticeably. Bit transparent output was verified at all supported sample rates. However, continuous playback of a single track was nearly impossible due to the aforementioned issues. CPU utilization was 10%-30% with 500 MB of 2 GB of memory in use during regular listening periods. Because the system CPU and memory utilization was identical when using ASIO and the other successful configurations I don't believe lack of system resources was an issue.
<ul>
<li>J River Audio Output Mode: ASIO.</li>
<li>Device: Xonar HDAV Slim ASIO.</li>
<li>Use large hardware buffers (J river recommended to prevent stutter): Enabled.</li>
<li>ASIO Buffering Size: 0.80 seconds.</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO set to 24 Bit.</li>
<li>ASUS software: ASIO Latency set to 80 ms.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="asio-pcm">graphic</a>)</li></li>
</ul>
</p>
<p><b>Xonar Essence STX - Working Configurations.</b>
</p>
The ASUS Xonar Essence STX is a very good consumer audio card. As I said previously it's a much more robust card than the less expensive Xonar HDAV1.3 Slim audio/video card. The STX card works great with all four preferred output modes, WASAPI - Event Style, WASAPI, ASIO, and Kernel Streaming. No matter what realistic configuration change I threw its way the STX card was unfazed. Sure the STX can't handle 5 seconds of WASAPI buffer, but I've yet to see a card that does support this unneeded amount. Here are four fully tested configurations that enable the Xonar Essence STX to sound very good. NOTE: When using the Kernel Streaming output mode make sure to select ASUS Xonar Essence STX Digital not ASUS Xonar Essence STX Audio as the output device (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/kernel-streaming-analog-digital.png" class="thickbox" rel="ks-digital">graphic</a>). Audio is equal to analog in the Kernel Streaming settings. If the incorrect device is selected the digital output will still send audio to an external DAC. However the audio will be resampled and the sample rate will not change automatically when switching between standard and higher resolution music. Since the STX was used in a Mac Pro with eight CPU cores the machine was less taxed during playback. The average CPU utilization was between 1% and 5% and memory utilization remained steady at 1GB with 9 GB free.
<p>
<b>One</b>
<ul>
<li>J River Audio Output Mode: WASAPI - Event Style. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-01-output-mode.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>Device: S/PDIF Pass-through Device (ASUS Xonar Essence STX Audio Device). (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-02-settings.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>Open device for exclusive access: Enabled. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-02-settings.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>Hardware Buffer Size: Minimum hardware size. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-02-settings.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>All DSP and Output Format settings disabled (unchecked). (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-03-dsp.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>Prebuffering: 2 seconds. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/wasapi-event-style-01-output-mode.png" class="thickbox" rel="stx-wasapi">graphic</a>)</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM.</li>
</ul>
</p>
<p>
<b>Two</b>
<ul>
<li>J River Audio Output Mode: ASIO.</li>
<li>Device: Xonar Essence STX ASIO.</li>
<li>Use large hardware buffers (J river recommended to prevent stutter): Enabled.</li>
<li>ASIO Buffering Size: 0.50 seconds (default).</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO set to 24 Bit.</li>
<li>ASUS software: ASIO Latency set to 50 ms. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-02-bit-latency-50ms.png" class="thickbox" rel="stx-asio">graphic</a>)</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="stx-asio">graphic</a>)</li></li>
</ul>
</p>
<p>
<b>Three</b>
<ul>
<li>J River Audio Output Mode: Kernel Streaming.</li>
<li>Device: ASUS Xonar Essence STX Digital.</li>
<li> Kernel Streaming Buffering: 0.50 seconds (default).</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="stx-ks">graphic</a>)</li>
</ul>
</p>
<p>
<b>Four</b>
<ul>
<li>J River Audio Output Mode: WASAPI.</li>
<li>Device: S/PDIF Pass-through Device (ASUS Xonar Essence STX Audio Device).</li>
<li>Open device for exclusive access: Enabled.</li>
<li> WASAPI Buffering: 0.50 seconds (default)</li>
<li>All DSP and Output Format settings disabled (unchecked).</li>
<li>Prebuffering: 2 seconds.</li>
<li>ASUS software: ASIO settings are automatically bypassed.</li>
<li>ASUS software: S/PDIF Out must be set to PCM. (<a href="http://images.computeraudiophile.com/graphics/2010/1217/stx/asus-asio-settings-01-pcm.png" class="thickbox" rel="stx13-asio">graphic</a>)</li>
</ul>
</p>
<b>Demonstration</b>
A common misconception about computer based playback is that software does not matter as long as the audio output is bit transparent. That is, as long as every single bit arrives at the external DAC in exactly the same shape it was when stored on the computer's hard drive there's nothing more to worry about. Over the last month I demonstrated countless times that two bit transparent audio streams from the same computer can sound very different depending on the software configuration. Thus, bit transparency is only the first step on the journey to great sound.
<a href="http://en.wikipedia.org/wiki/High_Definition_Compatible_Digital" rel="cash-stx"><img src="http://images.computeraudiophile.com/graphics/2010/1217/HDCD-logo.png" style="padding: 2pt 5pt 2pt 2pt;" align="left" alt="CASH-List"></a>Bit transparency testing - The HDCD indicator on the Berkeley Audio Design Alpha DAC is not foolproof, but there is a 99.99% chance that a computer is outputting bit perfect data if the HDCD indicator is illuminated upon playback of an HDCD encoded track. This is because the HDCD flag is located on the 16th and 24th bit of 16/44.1kHz and 24/44.1through 192 kHz content respectively. The 16th and 24th bits are consider the Least Significant Bits or LSB. If the HDCD indicator illuminates on the Alpha DAC, the data is uncorrupted. Theoretically, it is possible to alter HDCD data using specialized software while not touching the LSB, but all of the typical mechanisms that might alter data in a computer environment such as level shifting, dither, SRC’s, etc. will definitely affect the LSB. And, if the LSB is altered the HDCD code is lost. So, as a practical tool, presence of the HDCD light indicates no alteration of the data file. I've gone back and forth with my opinion about the validity of the HDCD bit transparency test. I've called it a great test and a rudimentary test, although two years separated these opinions. I've since discussed the effectiveness of using the HDCD indicator with Berkeley Audio Design's Michael Ritter. I shared my concerns about lighting the HDCD indicator even when the audio is choppy or when there are pops and ticks. Michael explained that this wasn't a bit transparency issue rather a data path issue. It's entirely possible to hear pops, ticks, and stuttering yet still send every bit in perfect shape to an external DAC. For example buffer under runs and over flows either starve or overwhelm an audio card with data. These conditions can last fractions of a second and are clearly audible even though every bit is transferred to the external DAC in pristine condition.
How does any of this relate to the ASUS audio cards? These two cards can demonstrate the affect software has on audio quality while still maintaining bit transparent output. In my experience the better the card design the less of an affect software may have on audio quality. I don't believe a combination exists (yet) where hardware is impervious to software even when using the best audio interfaces money can buy. Using the ASUS native ASIO driver with both of these cards results in two very different outcomes. The Xonar Essence STX appeared resistant to many ASIO configuration changes while the Xonar HDAV1.3 Slim was like a dandelion swinging in the wind. One small shift had huge consequences. On the same C.A.P.S. server that the Xonar HDAV1.3 Slim card was used, a Lynx AES16 performs flawless using an ASIO driver. Granted the ASIO drivers are different but one can see the importance of hardware / software interaction.
Getting to the heart of the above bit transparent misconception is easy when concentrating on the Xonar HDAV1.3 Slim card. I consistently demonstrated, at least to myself, its ability to output bit transparent audio using ASIO to my Berkeley Audio Design Alpha DAC. The HDCD indicator would illuminate when an HDCD encoded track was played. Using all sample rates there were periods of time when the audio sounded good, when the audio was littered with pop, tick, and stuttering artifacts, and when the audio was completely unintelligible. Digital audio is either bit transparent or it's not. When listening to music on this continuum from good to unintelligible there is a point where bit transparency is lost and the HDCD indicator no longer illuminates. Where that point is may be surprising to readers who've been told bit transparency is the be-all and end-all. During my listening sessions the point where bit transparency was lost was well beyond the standard pop and tick artifacts. All the bits arrived at the Alpha DAC in perfect condition but there were serious issues caused by the interaction between the ASIO driver and the Xonar HDAV1.3 Slim card. Minor adjustments to the ASIO latency settings had a clear cause and effect relationship with audible artifacts. Some readers may suggest that these clearly audible artifacts are red herrings and as long as there are no clearly audible pops and ticks there can be no difference in sound quality when the output is bit transparent. That's certainly a comforting thought to many audiophiles. However, the quality of one's audio system, the state of one's hearing degradation, and the level of one's listening ability have everything to do with the audibility of these artifacts. Anyone who has heard pops and ticks knows that not all of them are the same. Some are loud while others are barely audible. In fact many of us have wondered if some ticks were on the recording itself or caused by a system issue. Could a pop or tick just mean bits are missing? The simple answer is, I don't know. But if bits are missing bit transparency is lost and that was not the case during much of my time with the Xonar HDAV1.3 Slim card. I believe the data path may have had serious issues but every bit did make it to the DAC unchanged.
Far from a longitudinal scientific study or formal Audio Engineering Society paper, my work with the Xonar HDAV1.3 Slim card demonstrated a continuum from good clean audio to artifact filled audio that was caused by software adjustments. The whole time maintaining what I believe was bit transparency save the obvious unintelligible audio. To me it's evident that bit transparency is only the first step on the path to the highest quality computer playback. Hopefully the high end audio community will continue to research digital audio transmission between a computer and a DAC taking into account software variables. No matter how it turns out it would be nice to put this issue to bed and move on.
<b>Proven</b>
Spending such a long time with the ASUS Xonar HDAV1.3 Slim and Xonar Essence STX audio cards enabled me to get very familiar with each card's sonic signature. During this time I've proven to myself, and now maybe a CA reader or two, that inexpensive well designed audio cards are capable of really good sound. As I always say it's one's own opinion that matters. Proving the validity and value of a product is best done for oneself in his own system with his own music.
In my system the ASUS Xonar HDAV1.3 Slim card sounded good overall with one major weakness. On all types of music and at all frequencies this card sounded thin or anemic. Bass notes were shy and restricted where they should have been stern and violent during Passacaglia performed by the Kansas City Symphony on Reference Recordings' Britten's Orchestra at 24 bit / 176.4 kHz (<a href="http://www.referencerecordings.com/HRx120_DETAIL.asp">HR-120</a>). Listening to Bolero! - Orchestral Fireworks (<a href="https://www.hdtracks.com/index.php?file=catalogdetail&valbum_code=030911109226">RR-92</a>) it's evident from the first notes of the first track, Kabalevsky: Colas Breugnon, Op. 24 - Overture, that something is missing from the sound. There is no shimmer to the cymbals or pinpoint ring of the bells. The word that comes to mind over and over again is thin. There's a thinness to the sound that this cards imparts on the audio. Most other facets of this card's audio performance are good. The ASUS Xonar HDAV1.3 Slim is a really good cost effective A/V card that will squeeze into many music servers when the other larger cards cannot.
The ASUS Xonar Essence STX is a really good audio card capable of sonically challenging the more expensive competition. To challenge does not mean to surpass or even equal. Challenging in this context is somewhat like an underdog football team that can hang in there with the best teams for the first three quarters. After that the stamina, experience, and skills of the other teams are too much for the underdog. I compared the ASUS Xonar Essence STX directly to the Lynx AES16e and even the stratospherically priced Merging Technologies Mykerinos card. The Xonar Essence STX does so much so well it would be foolish to overlook this card, in favor of the expensive competition, when assembling a music server. The ASUS card can't compete when it comes to the benefits of external clocking and tons of professional features that simply aren't available on the STX. Fortunately most consumers don't need or care about all the extra features and would rather spend the money saved on music. Sonically the Xonar Essence STX is head and shoulders better the HDAV1.3 Slim and comes up a tad short against the Lynx cards. The main sonic signature of the Xonar Essence STX is actually something that many readers may enjoy. This card has big-time bass. This bleeds a bit into the mid-bass manifesting as a much fuller sound than the HDAV1.3 Slim card. The only issue I have is this bass is a bit too pumped up for my taste and may overpower low level details. Fans of rock music using Wilson Audio speakers should feel quite a visceral impact with the Xonar Essence STX card in their music server. The "enhanced" bass should help move some serious air into the room. On many tracks the bass had a coolness factor to it, but this coolness turned to annoyance when listening to the new <a href="http://bravurarecords.com/">Bravura Records</a> free 2010 Christmas downloads. These tracks are so well recorded and performed by such talented musicians that I just needed to hear everything on the recording as it was meant to be heard. With the highest quality audio cards all the fine details were crystal clear even when powerful but accurate bass notes were present. Not so with the Xonar Essence STX. If I knew more about drums and guitar I'm willing to bet I could identify the cymbals and sticks used by Simon Phillips and the bass strings used by Jimmy Johnson on Carol of the Bells by simply listening to the track a couple times. But only when listing through a card as good as my Mykerinos. Everything comes with a price. The price of hearing every last detail with a Mykerinos card is several thousand dollars above the Xonar Essence STX and even the Lynx AES16e. For many computer audiophiles the price of the last few percentage points of detail simply does make sense. A $199 ASUS Xonar Essence STX should make a lot of sense to everyone. Even to the most jaded audiophiles.
<b>Conclusion</b>
<a href="http://images.computeraudiophile.com/ca/cash-logo-black.png" class="thickbox" rel="cash"><img src="http://images.computeraudiophile.com/ca/cash-logo-black-thumb.jpg" style="padding: 2pt 5pt 2pt 2pt;" align="left" alt="CASH-List"></a>Over the last 18 months I've become very familiar the ASUS Xonar HDAV1.3 Slim and Xonar Essence STX audio cards learning everything from sonic signatures to preferred software configurations. Neither the HDAV1.3 Slim nor the Essence STX are the holy grail of audio reproduction, but I'm confident both cards can deliver on their value propositions given the right configuration and audio system. The HDAV and STX cards are capable of outputting bit transparent audio via electrical (coaxial) S/PDIF at all ample rates from 16 bit / 44.1 kHz through 24 bit 192 kHz. That's more than most companies can say about their consumer grade audio cards. The more discerning listeners should definitely select the audio only (<a href="http://www.computeraudiophile.com/content/Computer-Audiophile-Suggested-Hardware-List">C.A.S.H. Listed</a>) Xonar Essence STX card as it's much more robust and competes with cards many times its price. Computer Audiophiles looking for the most bang for their buck should look no further than the ASUS Xonar Essence STX.
Product Details:
ASUS Xonar HDAV1.3 Slim
<ul>
<li>Price: $150</li>
<li>Product Page: <a href="http://www.asus.com/product.aspx?P_ID=SPZfqXDJvadmFPoh&templete=2">Link</a></li>
<li>purchase link: <a href="http://www.google.com/products/catalog?hl=en&q=asus+xonar+hdav1.3+slim&um=1&ie=UTF-8&cid=11233560422114844185&ei=9hkJTaSaDuSW4gbPptCgAQ&sa=X&oi=product_catalog_result&ct=result&resnum=3&sqi=2&ved=0CEAQ8wIwAg#">Link</a></li>
<li>User Manual: <a href="http://files.computeraudiophile.com/2010/1217/e4232_Xonar-HDAV-Slim_UM.pdf">Link</a> [pdf]</li>
<li>Software Used: Version*7.12.8.1792 (Released 11/05/2010) <a href="http://files.computeraudiophile.com/2010/1217/HDAVslim_7_12_8_1792_Win7.zip">Link</a> [zip]</li>
</ul>
ASUS Xonar Essence STX
<ul>
<li>Price: $199</li>
Product Page: <a href="http://www.asus.com/product.aspx?P_ID=zCDHPnfR1jymHK2f&templete=2">Link</a></li>
Purchase Link: <a href="http://www.google.com/products/catalog?q=xonar+essence+stx&um=1&ie=UTF-8&cid=12150061145821736264&ei=CcULTfSwJomjnQfM1sXxDQ&sa=X&oi=product_catalog_result&ct=result&resnum=3&ved=0CEAQ8wIwAg#">Link</a></li>
User Manual: <a href="http://files.computeraudiophile.com/2010/1217/e4285_Xonar%20Essence%20STX_UM_0413.pdf">Link</a> [pdf]</li>
Audio Test Report: <a href="http://files.computeraudiophile.com/2010/1217/e4253_Xonar_Essence_STX_Audio_Test_Report.pdf">Link</a> [pdf]</li>
OPamp Instructions: <a href="http://files.computeraudiophile.com/2010/1217/Xonar%20Essence%20STX%20OPamp%20swapping%20instruction.pdf">Link</a> [pdf]</li>
Software Used: Version*7.12.8.1792 (Released 10/29/2010) <a href="http://files.computeraudiophile.com/2010/1217/PCI_STX_7_12_8_1792_Win7.zip">Link</a> [zip]</li>
</ul>
Associated Equipment:
<a href="http://files.computeraudiophile.com/2010/0418/Brochure_Fidelio.pdf">Verity Audio Fidelio loudspeakers</a>, <a href="http://www.mcintoshlabs.com/products/mcintosh-mc275-vacuum-tube-power-amplifier.asp">McIntosh MC275 amplifier</a>, <a href="http://www.richardgrayspowercompany.com/products.aspx?type=accessories">Richard Gray's Power Company High Tension Wires</a>, <a href="http://www.berkeleyaudiodesign.com/">Berkeley Audio Design Alpha DAC</a>, <a href="http://www.computeraudiophile.com/content/Computer-Audiophile-Pocket-Server-CAPS">C.A.P.S. server</a>, <a href="http://www.dcsltd.co.uk/product/debussy-dac"><i>d</i>CS Debussy DAC</a>, <a href="http://www.kimber.com/products/interconnects/digital/usb/bbus/cu/">Kimber USB Cu</a>, <a href="http://www.kimber.com/products/interconnects/digital/usb/bbus/ag/">Kimber USB Ag</a>, <a href="http://www.benchmarkmedia.com/system1/digital-analog-converter/dac1-pre">Benchmark DAC1 PRE</a>, <a href="http://www.kimber.com/products/interconnects/analog/select/singleended/ks1011/">Kimber Select KS1011 Analog Cables</a>, <a href="http://www.kimber.com/products/interconnects/digital/select/ks2020/">Kimber Select KS2020 Digital Cable</a>, <a href="http://www.kimber.com/products/loudspeakercables/monocle/x/">Kimber Monocle X Loudspeaker Cable</a>, <a href="http://www.apple.com/ipad/">Apple iPad</a>, <a href="http://www.amarraaudio.com/">Sonic Studio's Amarra 2.1</a>.
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