ASUS Xonar Essence ST/STX soundcards Page 3

The Xonar Essence STX was doing sterling work for my everyday listening. How would it stack up against other computer-audio solutions?

My first comparisons were with a slightly more expensive product, the $300 Logitech Squeezebox, which accepts audio data over a WiFi or Ethernet link, but is limited to 16 bits resolution and a sample rate of 44.1 or 48kHz. Source was the Squeezebox Server program (originally called Squeezecenter) playing files from the iTunes library on my Mac mini, and levels were matched to within 0.1dB at 1kHz.

Ah, that's what I was missing with the Xonar card—a remote control! And the joy of having a display that I can read from my listening chair. But the Squeezebox's sound, with its standard power supply, fell a little short of the Xonar Essence's. The bass lacked extension and the highs were grainier. When I played the master files of my recording of Cantus's While You Are Alive (CD, Cantus CTS-1208), the soundstage for Eric Whitacre's Lux Aurumque was less well developed, the hall sounding a bit smaller and drier.

The second round of comparisons were against a product that has become our de facto standard for high-end computer playback: Ayre Acoustics' QB-9 D/A processor ($2500), which features a USB input operating in the jitter-eliminating asynchronous mode (see Wes Phillips' review in October 2009). Again the source was my iTunes library, this time played from the Mac mini using iTunes, controlled with my iPod Touch via Apple's Remote app, and levels again matched at 1kHz.

Well, as much as I want to tell you that the $200 Xonar Essence equaled the $2500 Ayre, it didn't. Low frequencies had even more authority, high frequencies were silkier, and the Essence's soundstage was revealed as being flatter, with less image depth than with the QB-9. Yes, the iTunes-Mac-Ayre combo is irritating in that every time you want to play a file with a different sample rate, you have to exit iTunes, reset the sample rate in the Audio/Midi setup utility, then reopen iTunes. But the sound from the Ayre on hi-rez files was up with the very best. And, of course, the QB-9 will handle 88.2kHz files in a bit-transparent manner, though it won't, without a forthcoming firmware/hardware upgrade, decode files with sample rates of 176.4 or 192kHz.

But in the immortal words of the inestimable Sam Tellig, there was simply more there there with the Ayre. On "North Dakota," Lyle Lovett's duet with Rickie Lee Jones from Live in Texas (originally CD, Curb MCAD-11964), the delicate space around the electric guitar solo and the congas was more easily resolved through the QB-9, with both instruments being set farther back in the stage as a result. The Essence was very good, but the QB-9 was all I could imagine wanting or needing. For 12 times the price, of course.

Headphone listening
That the Xonar Essence cards have a dedicated headphone output is a boon for late-night listening. And the fact that their maximum output level can be adjusted to match the impedance and sensitivity of your 'phones is a blessing. I don't have the space here to go into the cards' sound quality with headphones—I will do so in a Follow-Up—but suffice it to say that the Essences did well in this mode.

Summing up
The Xonar Essence STX and Essence ST soundcards are by far the least expensive way of turning a PC into a genuine high-resolution audio source I have yet encountered. Neither the Essences' resolution nor their low levels of noise are compromised by having to operate in the electrically unfriendly environment of a computer chassis.

Assuming that the problems I encountered using the Xonar Audio Center to play files at 96 and 192kHz were specific to my computer/operating-system setup, both cards worked reliably, and using the ASIO4 virtual playback device (or later, the Wasapi driver) did resolve those problems. However, given the increasing number of high-quality files being offered for download with sample rates of 88.2 or 176.4kHz, their omission is a major impediment to my giving either of these cards a universal recommendation. And the fact that the Essences are compatible only with PCs is a problem for those who, like me, have found the Mac a more friendly environment for playing music from a computer. But for playing back CD-sourced files, I can unreservedly recommend the Xonar Essence, in either of its guises, as the least expensive means of extracting true high-end sound from a PC.

ASUSTeK Computer Inc.
US distributor: ASUS Computer International
44370 Nobel Drive
Fremont, CA 94538
(812) 282-2787

Xavier Xerxes's picture


Thanks for your review.  I would like to use the digital and analog output connections at the same time: digital for my home theater 5.1 experience and the analog to be connected to a 12-zone amplifier.


Is it possible that both digitial and analog output signals can work this way?



Andrei's picture

I am running two of these beasties.  One an ST and the other an STX.  For my part I have never had a problem with either playing resolutions of 44.1, 48, 96, & 192.  Sound quality was already good and took a giant leap forward when I upgraded the op-amps (a very cheap exercise).

Now the tricky subject of resolutions of 88.2 Khz and 176.4 Khz.  In fact there is a workaround.  If you have the free Audacity software it can be done.  Audacity is one of those freeware programs that are just outstanding.  What you do is this: (1) you simply load the track to be played.  (2) you play it back in Audacity.  So you do not use Foobar or MediaMonkey or Windows Media player or the like.  Now here is the curious thing: when using Audacity for playback it actually sounds better than even Foobar, my current favorite.  Audacity is a progarm for manipulating sound, rather than playback, but it naturally has a playback feature so you can hear the effects you have done.  What I think is happening is this:  Audacity rips the track into memory as some sort of wav format and hence the bit-rate / resolution is no longer relevant.

While I am on this subject: I found a small improvement by running a co-axial into a dedicated DAC.  This is not really necessary and hardly justifies the expense because the Xonar ST and STX already have excellent DACs.  The cost is a lot because you will need not only a better DAC but the cabling has to be good too.

Mirko's picture

Thanks for the great and informative review.  I bought this sound card with the intention of streaming spdif out to my pioneer 09tx so I could listen to high def FLAC on my stereo system.   I had no idea that the quality of the card actually makes a difference when using spdif out.  Which is contrary to what most people write about spdif.  Often you read that it doesn't matter and that bits are bits.  But i found this actually isn't the case.  If you don't believe me, try for yourself.  I thought I could live w/ my motherboards Realtek spdif out to my receiver and let the receiver  do the decoding.  But noticed that My realtek spdif sounded like crap!!! ESPECIALLY when comparing against the sound files the receiver decoded from usb or the ipod dock.  So I considered an external DAC, but I know that my receivers dac uses wolfson 8741 chip which Is already good. Anyway, after hooking up this asus bad boy, i was blown away by the worldly difference in sound that it made.  Setting the output on the card to PCM 192khz and I'm all set.  Mission accomplished.  But that's not all.  After comparing the analogue sound of the card, i was again, quite impressed...which one did i like better? My receiver to decode or the asus PCM chips?  i did A/B comparison with the asus doing the decoding versus the pioneer by running a long 1/4" jack and setting the volume level the same between the two.  Let me tell you, for 200 dollars, this asus card does a seriously good job providing a crisp clean and open analogue signal to your ears. I still prefer the my receivers dac by wolfson chips.  The sound is a little more smoother and less harsh to my's different but not better.   But I killed two birds with one stone on this one.  For two hundred dollars I got an excellent digital transport to my receiver, and high end audio analogue outs from my computer that are clear, clean an extremely quiet.  Very happy customer here.  To think that there are people out there running spdif from  crappy cards to thousand dollar external DACS is sad to me.  Maybe I'm wrong..anyway.  Awesome card.  Awesome buy.  Killer sound.  Makes me wonder if I would be able to discern the difference from this card and the essence one.  


Andrei's picture

Hi Mirko

I agree the sound quality is really good.  My other Source is a Cambridge Audio 650BD (not counting a turntable). Overall the Asus Xonar ST eclipses it by a tad.  The comparison is a bit tricky though because (i) I have upgraded the op-amps; (ii) the CA 650BD does play DVDA and SACD.  But on an Apples to Apples Comparison CD vs Flac at 16bit 44.1 Khz : the Asus Xonar card is a smidge better.  It becomes even better when I play flac files at 24bit and 48, 96, and 192 Khz.  On the other side the CA650BD is a bit better when playing DVDA and especially SACD.  The CA 650BD is not high-end to be sure but it is not bottom end either.  I think for 'spare change' the Asus Xonar cards are simply fabulous.  Why anyone would buy a Music Sever when they can have this card?

Initially I used the RCA connections direct to the AMP.  Then I tried SPDIF optical, and USB into an external DAC.  Finally I tried SPDIF coaxial into an external DAC.  USB was easilly the weakest and SPDIF via co-ax is easily the best sound quality.  The caveat is that you do need good cables.  


Andrei's picture

Oops.  Ignore the USB comment above.  I actually have two of these soundcards, or rather an ST and an STX.  With the STX that I use in my office it is connected to Bowers and Wilkins MM1 Desktop speakers.  They have the USB connection option to the PC.  With this Soundcard I connect via a RCA to Stereo plug.  It is this USB connection that I had tried and is not as good as using the Asus Xonar soundcard.


hollowman's picture

Selecting 192k Sample Rate in Xonar's Audio Control Center gives best performance of std. 16/44.1 in my tests. Wish the Control Center allowed more direct DAC control, such as selectable digital filter (Slow/Sharp) and phase reversal. 

Agree that this Card is a decent value. Since Asus decison-makers (and Asus' direct competitors, like HTOmega) are probably reading these comments, here are three suggestions for future products:

1. Use dual DACs in diff mode

2 Use better DACs, such as ESS Sabre

3. Design/offer more advanced firmware filters (prefer. user selectable) and upsampling. This may be via decoder DSP or simply selecting amongst those innate in DAC chip. E.g., Min. Phase, Apodizing, etc. Also allow selectable upsampling.

That's all! #3 requires no costly PCB/topological redesign -- it's just software code re-writing. #1 and #2 can be done w/o too much PCB redesign. The Sabre chip maybe $20-30 more, but I'll be glad to pay that for the huge gain in performance.

Thx for your attn.!

Shalmaneser's picture

I'm looking for cable advice for my Essence STX II -> Yamaha CX A5000 connection. I don't have anything local for easy comparison. I don't go for marketing of oligonucleotides injected into titanium mono-filament cables jacketed with carbon nano-fibre woven kevlar bulletproof sleeves. (lets keep it somewhere under $6 a foot.)

Shalmaneser's picture

Does anyone have a guide to the various opamps that are usable in the STX II? I can't even find anything that characterizes the included/extra opamps that ship with the STX II. Thanks!