| ASUS Xonar Essence STX PCI-E Sound Card |
| Reviews - Featured Reviews: Audio | |||||||||||||||||
| Written by Vito Cassisi - Edited by Olin Coles | |||||||||||||||||
| Thursday, 16 December 2010 | |||||||||||||||||
ASUS Xonar Essence STX PCI-Express Sound Card ReviewHumans have five main senses; touch, taste, sight, smell and hearing. Modern computing strives to advance the integration of these senses to produce stimulation during interaction, whether it be for games, movies or writing lengthy documents like this one! Naturally, some senses are more difficult to implement in an appealing manner, such as taste - silicon doesn't taste too good! Stimulating some senses may cause concern. The only time you're going to get a smell out of your PC is when you fry something, releasing the soul of the device in the form of a cloud of white smoke. Not to mention touch, which is wonderful on phones, and painful when you press your fingers against an overclocked northbridge. But the sense we're here to discuss isn't either of these. It's hearing. People spend hundreds on their CPUs, GPUs, motherboards, storage and memory, but dedicated sound is oft considered an unnecessary expense. Why pay for a card when your motherboard has a Realtek chipset? ASUS refuse to believe that onboard sound is enough. In our possession is their flagship audiophile audio card, the Essence STX, prepped for rigorous testing here at Benchmark Reviews. They claim "ultra-high fidelity" sound, and a remarkable 124dB signal-to-noise ratio on the front output. Will the onboard solution take a thrashing by this menacing card, or are enthusiasts correct in sticking with whatever their motherboard supplies? Audio cards are often used by audiophiles, and those who work with music at a professional level. Factors such as noise, amplification, circuit quality, API extensions (such as EAX) and DSP effects (such as Dolby Headphone) are all valid considerations which deciding between audio solutions.
A short reflection on the state of modern mainstream musicSound has come a long way since the days of using the internal speaker of a PC for nothing more than beeps and boops. CD quality audio is commonplace, yet convenience is frequently prioritised ahead of quality. MP3 files are popular because of their size, and their suitability for storage limited devices. The downside to MP3 is that it's a lossy compression format, meaning that the audio is stripped of data to save space. In theory the data which is trashed is inaudible to humans, but in practise even the best compression methods cause some level of quality degradation. An alternative to MP3 is FLAC. FLAC, or Free Lossless Audio Codec, is exactly that - a lossless compression codec. Vaguely similar to how zip files work, FLAC compresses audio without permanently removing data. This requires decompression during playback. Unfortunately, despite a significant growth in storage and Internet speeds, MP3 remains the dominant format for digital music. Formats aren't the only indicator of quality. Apart from the obvious (being the quality of the recording gear/setup and instruments) there's the matter of dynamic range, or perhaps more importantly, dynamic range compression. To put it simply, the dynamic range of an instrument or piece of music is the ratio of the loudest sound to the softest. For example, the softest sound may be the subtle whisper of a backup singer, and the loudest the beat produced by drums. Dynamic range compression is when you reduce the difference between these soft and loud notes to make everything louder. This is often used in modern mastering to make music sound louder than it should be, to compete on mediums such as radio or television. The end result is a lifeless track, stripped of its musical integrity. So why is it done? It's part of the so-called Loudness War. You can read more about this phenomenon here (including some audio examples), or at Wikipedia here. Why does all this matter? When reviewing or leisurely listening to a sound device, subjective judgement is based on listening to music. A perfect audio card (if one should ever exist) would reproduce sound exactly as the audio file dictates. However, just like any system, if you put rubbish in, you get rubbish out. This is important, because a good audio device can make bad music sound worse, since it becomes easier to distinguish imperfections which are part of the audio files 'instructions'. For this reason, music will be carefully chosen during the subjective analysis of this card, in addition to a range of headphones.
Manufacturer: ASUSTeK Computer Inc. Full Disclosure: The product sample used in this article has been provided by ASUS. Closer Look: ASUS Xonar Essence STXThe Essence STX uses a slick black PCB to house its components. The bracket is coloured gold to match the gold plated TRS sockets, which adds a touch of class.
A black brushed-metal electromagnetic shield covers the analogue components to ensure quality output.
From left to right are the right/left RCA connectors, TRS (6.35mm) line out/in, and optical S/PDIF out.
Included is a S/PDIF TOSLINK adapter, and a 3.5mm to 6.35mm TRS adapter. There's also a 3.5mm-to-RCA adaptor cable to allow 3.5mm devices to use the RCA connections.
Along the top of the card are the auxiliary input and front panel connections. The auxiliary connection is used for input from other devices such as TV tuner cards.
The molex connection provides power to the Texas Instruments TPA6120A2 headphone amp. Beside it is an alternate S/PDIF out header.
All considered, the Essence STX has a great selection of inputs. It's nice to see 6.35mm TRS jacks being used instead of 3.5mm connections. ASUS Xonar Essence STX Detailed FeaturesUnderneath the EMI shield is the circuitry responsible for analogue output. This is where the user-swappable op-amps are located.
The DIP8 sockets for the op-amps (of which two have been removed).
To the left is the op-amp responsible for RCA out (LM4562NA), and to the right is the 2114D op-amp responsible for left/right headphone (TRS) out. There are two of the latter, one for each left and right channel. These op-amps are of high quality, so their replacement is not essential unless you're into tinkering with sound.
This is the main processing unit on the card, the ASUS AV100 HD audio processor. It's responsible for Aural 3D (A3D), DirectSound/DirectSound3D and OpenAL processing.
A Cirrus Logic CS5381 ADC (Analogue to Digital Converter) is used to convert the analogue line-in into digital signals.
New JRC5532 and Texas Instruments R4850 op-amps are used for line-in/microphone input.
With all this fancy high-quality circuitry doing the heavy lifting, let's take a look at the software which drives it. ASUS Xonar Audio Center SoftwareASUS bundled their Xonar Audio Center software with the card. This software is similar across all the Xonar products, with small changes specific to particular models. In this screenshot we have the main screen showing the currently enabled modes, master volume, and frequency bands. There's also the option to change the number of audio channels, sample rate, and the analog output (i.e. 'Headphone', '2 Speakers', or either via the front panel). Along the bottom of the blue status area are the available Dolby technologies. These include Digital Live, Headphone, Pro Logic IIx, and Virtual Speaker. Digital Live encodes audio into a 5.1 channel 16-bit/48 KHz signal in real-time over S/PDIF. 'Headphone' allows stereo headphones to emulate the positional audio effects of a discrete 5.1 surround sound set up. Pro Logic IIx up-converts stereo or 5.1 channel audio into a 6.1 or 7.1 channel signal. 'Virtual Speaker' is similar to 'Headphone', but is suited to any set of stereo speakers.
The mixer allows the adjustment of the left and right channels. Hitting the 'Record' button gives us further options for MIC, line-in, aux, Mix and Wave volumes.
Environmental effects simulate different sound stages, whilst the equaliser gives us control over the frequency response of the output. The latter is great for compensating for deficiencies you may identify in your audio equipment.
KARAOKE is a set of options to adjust key shifting, vocal cancellation, and microphone echo. These options were not tested, in fear of destroying the delicate STX with horrendously off-pitch vocal attempts.
FlexBass gives you control over the LFE (Low-frequency effect) crossover frequency. Basically, this moves low-frequency (bass) signals from satellite speakers to your subwoofer. This can improve bass quality.
VocalFX gives the user a few options for in-game chat and VOIP. VoiceEX can be enabled for the former (which adds EAX effects), and the latter has options to annoy people with 'ChatEX' environmental effects and 'Magic Voice' voice alterations.
Evidently, ASUS have produced a respectable software solution for their Xonar range of cards. The aesthetically pleasing style and functionality make it a valuable asset. It does have some quirks, such as the volume dial which is counterproductive for interaction via a cursor, but that's being a tad pedantic. On the other hand, the five small preset buttons to the right make it super easy to quickly swap between modes such as Hi-Fi and gaming. If only they had associated keyboard shortcuts! ASUS Xonar Essence STX Features
ASUS Xonar Essence STX Specifications
Source: Features and specifications provided by ASUS Testing MethodologyTo test the ASUS Xonar Essence STX we have used RightMark Audio Analyser 6.2.3. This produces graphs which display the following aspects of an audio card:
Each of these tests will be run four times to ensure consistency, using an external loopback cable. If the results are consistent, the best result of the four will be used to offset error introduced by noise produced by the lengthy loopback cable.
In addition to these analytical tests, we will be listening to some music to gauge whether there's an audible difference, and whether the difference is an improvement. The tracks we will use for testing include The Wall pt. 1-3 and Shine on You Crazy Diamond by Pink Floyd, assorted tracks by Sarah Blasko including Bird on a Wire, and selected tracks from David Russell. These tests will be done with 'Hi-FI' mode enabled (which turns off all enhancements) within Xonar Audio Center.
The headphones used to run these tests include:
Test System
Listening Test ResultsThe first thing you notice when using the Essence STX over the onboard solution is how clear and defined instruments sound within a track. You can hear the softest of notes with utmost clarity. Tracks with a large dynamic range such as Pink Floyd's offerings come across spectacularly, with natural punchy bass and guitar strums which send shivers down your spine. These traits, however, are difficult to appreciate without a quiet room and high fidelity audio gear. The Alessandro MS1i were the best option here, but in all honesty, it's very difficult to hear the difference between onboard and the Essence STX in majority of cases. The Essence STX requires very good source audio, and equally grand equipment to be truly appreciated. Perhaps the most notable track during testing was David Russell's 'Tu Imagen'. The detailed strums of the guitar are simply unmatched by the onboard solution. It's this fine attention to detail which separates a good sound solution from an excellent one. Movies are amazing on the Essence STX. When set to 6 channels and with Dolby Headphone enabled, even stereo headphones sound convincingly surround. The Alessandro MS1i headphones aren't known for a large soundstage, yet the effect is still surprisingly good. The onboard solution struggled with claustrophobia-inducing lifeless sound. The movie iRobot was used for this evaluation. Gaming proved interesting. Just as movies sound great with Dolby Headphone, games come across as vivid and realistic. Enabling 'game' and 'GX' modes proved to be effective in games such as Unreal Tournament 3 and DiRT2. 'GX' mode enables EAX emulation for games which implement its API. Although the Essence STX doesn't have native hardware EAX support, it emulates it well. Again, the onboard Realtek audio processor struggled, with similarly constrained sound to the movie tests.
RightMark Audio Analyser ResultsSummary of Results (RCA out)
Note: The Realtek solution wasn't tested at 192KHz due to its lack of support for sample rates above 48KHz. Frequency Response (RCA out, 24bit 192KHz)
As you can clearly see, the frequency response is quite flat for frequencies audible by humans (about 15-20,000Hz). This is a great result by both cards. Unfortunately, the Xense pulls ahead in frequencies between 15KHz and 30KHz. Frequency Response (RCA out, 24bit 48KHz)
When compared to onboard sound, the Essence STX does a significantly better job. While the Realtek solution attenuates at frequencies north of 5K, the Essence holds out until 10K, and drops at a slower rate. The Xense does a better job but still emphasises frequencies above 10K. Noise Level (RCA out, 24bit 192KHz)
The RCA output of the Essence STX is rated at -124dB, and line-in at -118dB. Since we're using a loopback cable (that is, we're connecting the RCA out straight into line-in), the noise level is affected by the capabilities of the latter. We're also subject to noise introduced by the loopback cable itself, and any noise produced by the PCI-e and molex power connection. The noise levels of this card are very good. Noise Level (RCA out, 24bit 48KHz)
The onboard Realtek solution isn't even in the same league as the dedicated ASUS cards. There's about 30dB between them. Dynamic Range (RCA out, 24bit 192KHz)
Dynamic range tends to correspond to the absolute value of the noise level, so this excellent result isn't surprising. Dynamic Range (RCA out, 24bit 48KHz)
The card performs well compared to the onboard solution. Again, a 30dB difference between the Essence STX and the Realtek solution. The Essence STX has a slightly lower noise floor than the Xense. Total Harmonic Distortion (THD) (RCA out, 24bit 192KHz)
The THD here is well below 1%, and edges out the Xense by a small margin. A very good result. Total Harmonic Distortion (THD) (RCA out, 24bit 48KHz)
Consistent with previous results, the Realtek lags behind with a distortion level 123x that of the Essence STX, and 92.5x more than the Xense. The Xense has 1.33x the distortion of the Essence STX, giving the STX the winning result. Intermodulation distortion (RCA out, 24bit 192KHz)
Again, the distortion level is extremely low. Another stunning result. Intermodulation distortion (RCA out, 24bit 48KHz)
The somewhat batted onboard solution is outdone again with 65x the distortion of the Essence STX, and 30.5x the Xense. The Essence STX edges ahead of the Xense with about half the distortion level. Stereo crosstalk (RCA out, 24bit 48KHz)
Low levels of leakage between left and right channels is a good thing, as shown in the above graph. The onboard solution didn't fair as well, with significantly higher leakage across all frequencies. Headphone Out Tests The above tests were repeated using the headphone (TRS) out instead. Here's a summary of the results:
Overall, the Essence STX does a very good job. ASUS provide their own test results in a fancy booklet titled the "Audio Precision Test Report", carried out on professional testing gear. The tests carried out in this booklet are similar to those above. 7.1 Sound Card Final ThoughtsTesting audio components is always a challenge. While there's software such as RMAA which can give you an analytical look at the performance, it isn't as simple as hitting 'start' and then looking at graphs. Ensuring that your system isn't introducing noise into the signal is challenging, and in many cases, near impossible. The original test system was a X58 platform with an overclocked i7 920. However, when noise tests came back erratic, one could only imagine what was causing it. Was it noise on the PCI-e bus? Was the PSU providing 'dirty' power to the amplifier? Thermal noise? Or perhaps the lengthy loopback cable was being a nuisance? In the end, it came down to the either of the first three options, but even at stock, the audio was well below spec in terms of noise. I like to think that the motherboard was shouting profanities as it struggled to keep up with its heavy overclock, causing the meek STX to cower in fear. But in the end, it was probably just the hothead 4870x2 heating up the defenseless EMI shield! Fortunately, an older but capable system was used instead, and sane results were produced. These results were spectacular, with very low noise levels across the board, and a respectable frequency response. This is very much a card for audiophiles.
ASUS Xonar Essence STX ConclusionAs the performance graphs show, the ASUS Xonar Essence STX is a high achiever. It blitzed all tests, bar one, where the Xonar Xense got a slight upper hand in frequency response. The Essence STX absolutely obliterated the onboard solution in all tests, which is a good sign considering the asking price. Despite the lack of native EAX support, the Essence STX does surprisingly well in games. Dolby Headphone does wonders when paired with the emulated EAX environmental effects. The inbuilt amplifier gives headphones an added oomph, even if they're already easy to drive. Whether it be music, games or movies, the amplifier adds that little bit extra which makes all the difference. In terms of aesthetics, the Essence STX ticks all the boxes. Classy color scheme? Check. Brushed aluminium? Check. Chrome branding. Check. Looks great through a case window? Check. What more can we ask for? The construction quality of the Essence STX is as good as you can expect. The card is rigid and the materials are top-notch. When it comes down to functionality, we have to keep in mind that this card is aimed squarely at audiophiles. This being said, the Essence STX is excellent for more than just music. It's a capable movie and gaming card too, with Dolby Headphone producing outstanding results. Digital out and the provided TOSLINK connector allow external DACs to be used, and the gold plated TRS/RCA in/out facilitate clean noise-free audio. To top it off, the card has replaceable op-amps - something that's far from common, yet very handy for dedicated enthusiasts. NewEgg sell the ASUS Xonar Essence STX for $199.99. This may sound pricey, but you're getting a card which will last several upgrades. Audio equipment depreciates at a significantly smaller rate than your typical processing components (think CPU and GPU). When one can spend upwards of $500 on just the graphics portion of a build, a top of the range audio solution for $200 with greater longevity becomes enticing. Is the Essence STX worth $200? If you love your music, it's well worth your hard earned cash. Overall, the Essence STX is the best audio experience I've experienced on a PC to date. The only gripe I have is that it's limited by my audio gear! The quality of output is excellent, so future speaker upgrades won't be a concern. This, and the decision to use modern connectivity (such as PCI-e) makes this a true future proof audio card. Highly recommended. Pros:
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Comments
I am curious about the THD peak at 1Khz.
Is this something commonly seen?