Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 1

The PC Soundcard is a market that has been dominated by Creative up until fairly recently. Creative is a monolith seemingly wrapped up in it's own success and any innovation seems to come at the cost of quality.

This is where Asus steps in with their Asus Xonar Essence STX. Despite its long and convulted title, this card may be just be what the PC sound-card market has been waiting for - a proper SOUND card. You may be wondering what I am saying by that. Let's see what Asus say about it:

"Story behind the Masterpiece
Thousands of years ago, our ancestors crystallized their knowledge of the materials and music into the Chime of Tiger, one of the first audio masterpiece in human history. Gold-plated on the EMI shield, the Chime of Tiger totem not only represents Xonar teams new footnote in audio innovation, but also mankind's endless pursuit of the Essence of Sound."

Now what I really want to draw your attention towards is the last bit. Asus are after the "Essence of Sound" in this card. This is a card aimed at those who want excellent quality sound for music. It's not aimed at gamers and not at cinema buffs. It's aimed at those wanting to get the most out of their PC music collection. This is a good thing in my eyes. Sure you can grab an X-Fi and see how it does with music. I'm sure it would be perfectly adequate, but there's no mainstream cards that really do the trick with music.


Taken from Asus's website.

Audio Performance
Output Signal-to-Noise Ratio (A-Weighted):
124dB for Front-out,117dB for Headphone-out (600ohms) dB
Input Signal-to-Noise Ratio (A-Weighted):
118 dB
Output THD+N at 1kHz:
0.0003% (-110dB) for Front-out, 0.001% (-100dB) for Headphone-out
Input THD+N at 1kHz:
0.0002% (-113dB) for Line-in
Frequency Response (-3dB, 24-bit/192kHz input):
<10Hz to 90KHz
Output/Input Full-Scale Voltage
2 Vrms (5.65 Vp-p)
Bus Compatibility
PCI Express:
-PCI Express Rev. specification compatible
-Compatible with X1, X4, X8, X16 PCI Express slots
Main Chipset
Audio Processor:
ASUS AV100 High-Definition Sound Processor (Max. 192KHz/24bit)
24-bit D-A Converter of Digital Sources:
Texas Instruments PCM1792A*1 for Front-Out (127dB SNR, Max. 192kHz/24bit)
24-bit A-D Converter for Analog Inputs:
Cirrus-Logic CS5381* 1 (120dB SNR, Max. 192kHz/24bit)
High Fidelity Headphone Amplifier:
Texas Instruments 6120A2*1 (120dB SNR, 100dB THD+N @ Vcc±12V, RL=600, f=1kHz)
Sample Rate and Resolution
Analog Playback Sample Rate and Resolution:
44.1K/48K/96K/192KHz @ 16/24bit
Analog Recording Sample Rate and Resolution:
44.1K/48K/96K/192KHz @ 16/24bit
S/PDIF Digital Output:
44.1K/48K/96K/192KHz @ 16/24bit, Dolby Digital
ASIO 2.0 Driver Support:
Supports 44.1K/48K/96K/192KHz @16/24bit with very low latency
I/O Ports
Front-Panel Header
Shared by Headphone out / 2 channels out /
Microphone in S/PDIF Header: Connects to compatiable graphic cards for HDMI output Analog Output Jack:
RCA jack *2 (Front R / Front L), 6.30mm jack*1 (Headphone out)
Analog Input Jack:
6.30mm jack *1 (Shared by Line-In/Mic-In)
Other line-level analog input (for CD-IN/TV Tuner):
Aux-In (4-pin header on the card)
Digital S/PDIF Output:
High-bandwidth Coaxial/TOS-Link combo port supports 192KHz/24bit
Driver Features
Operation System:
Windows Vista/XP(32/64bit)/MCE2005
Dolby® Technologies:
Dolby® Digital Live
Dolby Digital Live encodes any audio signal on PC in real-time to Dolby Digital (AC3) 5.1 surround sounds to your home theater environment through one single S/PDIF connection

Dolby® Headphone
Dolby Headphone technology allows users to listen to music, watch movies, or play games with the dramatic 5.1-channel surround or realistic 3D spacious effects through any set of stereo headphones.

Dolby® Virtual Speaker
Dolby Virtual Speaker technology simulates a highly realistic 5.1-speaker surround sound listening environment from as few as two speakers.

Dolby® Pro-Logic II
Dolby Pro-Logic II is the well-known technology to process any native stereo or 5.1-channel audio into up to 6.1 channel output, creating a seamless, natural surround soundfield.
Smart Volume Normalizer:
Smart Volume Normalizer
Normalizes the volume of all audio sources into a constant level and also enhances your 3D sound listening range and advantages in gaming
Xear 3D Virtual Speaker Shifter:
Virtual 7.1 speaker positioning
Karaoke Functions:
Music Key-Shifting and Microphone Echo effects like professional Karaoke machine
Professional Bass Management/Enhancement system
3D Sound Engines/APIs:
Vista: DirectSound3D® GX 2.5, DirectSound® HW, DirectSound SW, A3D®1.0, OpenAL generic modes, 128 3D sounds processing capability

XP: DirectSound2.5 SW, A3D®1.0, OpenAL generic modes, 128 3D sounds processing capability
1 x 3.5mm-to-RCA adaptor cable (8ch)
1 x S/PDIF optical adaptors

A pretty beefy set of specs there with the most obvious omission being DTS decoding which is a little suprising. Note that the Dolby processing should convert the signal to 5.1 in this case, but I will be testing this.

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 2
Packaging and Contents

Asus have chosen to represent their Essence STX with a plain simple packaging displaying the 'Chime of Tiger' logo. It's certainly different and should stand out on the shelves.

packaging front  packaging rear
The rear of the box is a patchwork of information and whilst it looks good, it's actually pretty hard to make out the essential details.
flip up
Thankfully Asus provide a lot clearer information on the inside of the cover. The card is visible, something I always like to see. The information is arranged in a clear concise way.

The card and contents are well protected by a clear plastic covering which also shows off the card to it's advantage.

The package that comes with the Essence STX is actually more basic than I had expected if I'm honest.

You get:

• 2 x Xonar Essence STX Posters
• User manual
• Audio Precision Test Report
• 1 x RCA to 3.5mm jack adaptor
• SPDif pass-through digital Toslink Adaptor
• 3.5mm to 6.25mm headphone connector
Everything is there to do the basics, but with a £160 sound card, I did expect something else. Perhaps a Digital Optical cable or something. I'm perhaps being a little picky, but posters of the sound card are a little lame and I cannot see any audiophile putting them up.

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Asus's sound-cards are striking in appearance, if only for the fact that they have a fairly large EMI shield on them. The Essence STX is a decent looking card and is bound to look good in any windowed setup.

The Chime of Tiger symbol is again in evidence here with a gold symbol etched into the brushed aluminium cover on the card.

Xoanr front  rear card
The black PCB uses what Asus call Hyper-Grounding circuitry design. Seemingly this separates signal and noise to produce clear signals. You can clearly see the Nichicon "Fine Gold" professional audio capacitors, these are well respected in the industry and props go to Asus for including some of the best components on-board the card.
caps  audio chip

You'll also notice the Dolby certified symbol, always a good sign if you want decent surround sound.
top connection

The card supplies connections for front panel and AUX input in a small gap in the shielding.

The sound card must be powered to produce any sound at all and a 4 PIN molex connection is provided for the purpose.
And a gratuitous photo of the cover on the card to finish.

Outputs look sparse but provide all that an audiophile should need. Analogue RCA's sit with a 6.25mm Headphone jack (3.5mm adaptor included, see previous page). An SPDIF connection is also also included on the rear IO with a Optical Digital converter included. Input-wise on the rear IO, Asus provide a 6.25mm Mic jack which should please all those budding artists who want to plug their professional Mic into.

It's worth mentioning that solid capacitors aren't used in this card. The Auzentech X-Fi Prelude does include a multitude of solid state capacitors on-board, but these are not considered to produce excellent analogue sound, which is really what the Essence STX is about.

Now let's down to the nitty gritty...

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 4

At first I was a little worried that the Xonar Essence would come with the 'bloatware' that you see on X-Fi based cards. This type of driver and software really does turn you off getting a card if you just want it to produce good sound.

Luckily, I need not have worried. Asus have given you a slightly flashy user interface, but it doesn't feel clunky and everything is available right there in front of you, no switching of modes or anything like that.

UI main
Pictures is the main part of the UI where all of the input switching takes place. Here you can determine how many speakers you are using, what type of analogue output you would like and how you want the SPDIF to work.

Setting SPDIF to Dolby Digital Live immediately greys out the analogue outputs. Settings the analogue output to speakers means that the sound goes out through the analogue RCA out. Setting to headphone means the onboard headphone AMP is activated.

There is such a large combination of outputs you can have I don't have time to list them all here. Suffice to say there is a great range of outputs and it's great to have them all in one place.

The Mixer allows you to adjust left and right levels for output and adjust any input levels.

The Effect panel allows you to add a huge range of environmental presets (surprisingly) and EQ presets to your music. Those with any modern soundcard or half decent onboard sound will be familiar with this and familiar with the fact they don't improve sound much. The only one I found useful was "Padded Cell", which negates echo if you hear any.

Obviously here you can adjust your EQ settings if you so desire and it does have an effect on the music. The presets are there for the EQ but frankly there are always terrible and not worth using.

The Karaoke screen is a bit of fun. You can fiddle with this and have your own Karaoke sesh if you feel so inclined. It does work fairly well, but I'm afraid it just isn't my thing. I think I had better learn to sing before I even attempt it!

Flexbass is an interesting part of the package. It allows you to set the LFE Crossover to whatever you want, down to 50HZ. This is a good idea for those who want to ensure that their speakers are either getting the most bass possible, or ensuring that your speakers are only fed the higher frequencies.

VocalFX is another feature I didn't get a huge amount of time to play with. Perhaps best described in the manual:
VocalFX is an innovative voice processing technology to let your voice get into the realistic game landscape (VoiceEX) or to emulate the background scenes in online chat (ChatEX). It also allows you to change your voice pitch to disguise who you are (Magic Voice). These features dramatically increase the fun for voice communication on PC.

It's a decent idea and could possibly be useful in some scenarios, but mostly it's a bit fun really. Might be good for winding up mates!

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 5
Test Setup

For the excellent Asus Xonar Essence STX, I used the following PC equipment:

Intel Q6600 @ 3.3GHz
Abit IP35 Pro
4GB OCZ ReaperX PC6400 @ 1000MHz
MSI 8800 GTX
Seagate 7200.10 250GB HDD
Coolermaster Real Power Pro 1000w PSU
Belkin AV Home Cinema Surge Protector - 7 Socket
Asus Xonar Essence STX
Abit IP35 Pro onboard sound (Realtek ALC888 codec)
Auzentech X-Fi Prelude

To bring out the best in the sound card, I have used the following Audio setup:

Sennheiser HD555 Headphones

Denon AVR-1909 AV Receiver
Mordaunt Short 906i Floorstanders (Bi-Amped, silver coated oxygen free copper)
Mordaunt Short 905i Centre Speaker (Bi-wired, silver coated oxygen free copper)
Mordaunt Short 905i Bipole Rears (300 strand oxygen free copper)

Additional Cabling:
Tacima CS929 6 Way Mains Conditioner
IXOS XHD208-300 Toslink Digital Optical Audio Cable
IXOS XHA215-300 2 RCA to 2 RCA Stereo Audio Cable

I managed to grab an Auzentech X-Fi Prelude to match against the sound quality of the Xonar Essence STX. Whilst this is more of a 'gamers' sound card, I feel it represents the closest card that the market has to offer for sound quality.


Rightmark is an audio analyser designed for testing the quality of analogue (and digital) paths of audio devices. The results are obtained by playing and recording test signals passed through the tested audio path by means of frequency analysis algorithms. – Rightmark.

Noise Level  Stereo Crosstalk

IMD test  THD Test

The figures are good in the tests, with a compliance to the standard and above. I was not happy with the connection I had to use for the noise level tests as I could not get hold of the correct wire before running the tests. The noise level gained in the test was taken at approximately 60% volume, for example. Even this inaccuracy aside, the sound card was far superior to any onboard sound and subsequently is better that that of the X-Fi preludes (not shown).

CPU Utilisation

Here we see how much of an impact using the Xonar's software based emulation has on the CPU. Results are again provided by a Righmark piece of software, this time Rightmark 3D Sound CPU Utilisation test.

(CPU Utilisation set at 16-bit/44.1KHz – 16 buffers)

(CPU Utilisation set at 16-bit/44.1KHz-128 buffers)

(CPU Utilisation set at 24-bit/96KHz 16-buffers)

(CPU Utilisation set at 24-bit/96KHz-128buffers)
The Xonar Essence stayed well below 4.5% CPU utilisation during all CPU utilisation tests. This shows that even during 24bit, 96KHz, 128buffer Direct3D Sound with EAX playback, the Essence won't take up much of your processing time at all. As the saying goes: 'time is money' and the Xonar Essence STX saves your CPU time, dedicating it to playing games or whatever you are doing at the time!

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 6
Gaming - testing

To test the Xonar Essence with games, I pitted it against the X-Fi Prelude. With it's Creative Technology inside, how would the Xonar Essence fair in an area it isn't necessarily designed to work in?

I tested a wide range of games to see how the card coped with each game. FPS graphs below are from a small selection. I set the control panel to both multiple speaker and headphone modes to test how the Dolby Digital Live conversion sounded.

Unreal Tournament 3

An Unreal Engine 3 game as it is a fast, frantic and furious multi player mash-up experience. Using advanced DirectX 9.0c features, the Unreal Engine looks fantastic and has a lot of explosions all around to give that feeling of depth. PhysX was not enabled in-game.

Settings: 1920 x 1200, Very high settings. The UT3 Benchmark was used for all cards.

UT3 headphone

The Xonar keeps up with the Auzentech X-Fi Prelude, perhaps an FPS or two below the Prelude.

UT3 surround sound

Surround sound puts the FPS down very slightly but you will notice the Essence XTS keeps up with the X-Fi based card.

Quake 4

Quake 4 is a game built on the Doom 3 engine. This uses many DX 9.0c features based on OpenGL game. Once again I did three benchmark runs on Quake 4 on each card and took the average of all my readings from these. The Quake4Bench demo was used to benchmark all cards.

Settings were: 1920 x 1200, Ultra settings. 16 x AF, 4 x AA. Multi-CPU enabled.

quake 4 headphone

A little higher FPS difference between the Asus card and the Auzentech shows in Quake 4. The settings were set to a very high level which was very challenging on my awesome 8800GTX.

quake 4 surround

The difference is evened up here as the Asus's fantastic Dolby Digital live processing kicks in in Multi-channel mode.

Gaming sound

I have to note that whilst most games ran very well, there were a few that had some glitches, especially with the release drivers. Whilst the updated drivers fixed a lot of these, some games had slightly odd sound and some didn't sound quite like the surround sound was working properly. These games were mostly those that relied on high levels of EAX support to give surround sound.

These issues aside, the sound was superb in both headphone and multi-channel sound from the mighty Asus Xonar Essence STX. Headphone sound especially was detailed and punchy and you really felt those headshots!

The Asus Xonar Essence STX isn't the best gaming sound-card you can buy, but it's not aimed at that market, unlike the Auzentech X-Fi Prelude. It does very well in almost every game out there and Asus are constantly looking to improve their drivers so the one or two games I heard slight glitches in occasionally will, I'm sure, be sorted.

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 7
What the Asus Xonar Essence STX is all about - Sound Quality

To ensure I really tested the Asus Xonar Essence STX properly, I played a large variety of music from my eclectic collection, including playing CD's and extracting high quality FLAC recording  from several CD's. I have tried to cover a large range of music genre's to ensure I tested all aspects of the sound coming from the card. Note I also listened to normal MP3's and AAC compressed tracks to ensure I portrayed a 'real world' situation.

All tracks were listened to in analogue and digital, both through the AMP and through headphones.

Example tracks used:

• Sultans of Swing - Dire Straits
• Adele - Chasing Pavements
• Bloc Party - Luno
• Bob Marley - Three Little Birds
• Chemical brothers - Block Rockin' Beats
• Damien Rice - Cannonball
• Foo Fighters - Skin and Bones
• Fugees - Killing Me Softly
• Goldfrapp - A&E
• Jamariqui - Virtual Insanity
• Feff Buckley - Hallelujah
• Led Zepellin - Black Dog
• N.E.R.D. - Lapdance
• Pendulum - Slam
• Prodigy - Omen
• Robert Miles - Children
• Roni Size - Brown Paper Bag
• Snoop dog - Beautiful
• Paul Gilbert - Radiator
• Paulo Nutini - New Shoes

To test the surround sound capabilities of the Asus Xonar Essence STX, I listened to the following UK DVD's using Cyberlink PowerDVD. I listened in both headphone and surround mode. DVD's used:

• The Matrix (DTS)
• Lord of the Rings: The Two Towers (Dolby Digital)
• The Bourne Identity (DTS and Dolby Digital)

Sound Quality - Music (Digital Sound)

Digital sound produced a balanced sound-stage for music with clear highs and a detailed mid-range with a reasonably punchy low. At times I felt as though there was something lacking in the sound and that there was something missing somewhere though. Tracks like 'Slam' and 'Block Rockin' Beats' sounded great but not quite what Asus promised.

On direct comparison though, the Auzentech prelude's digital sound was very similar. Perhaps missing some of the detail of the Essence STX, but a nice sounding fairly well-rounded sound.

Utilising the Dolby Digital Live and Pro Logic Modes on the Xonar Essence STX produce decent enough sound and certainly filled my speakers well enough. It is hard to believe that any audiophile would use these sound 'enhancements' as they only serve to muddy the music and not benefit it.

Sound Quality - Music (Analogue Sound)

three little birds  lune  Slam  Sultans of Swing  Lapdance


Connecting the Ixos RCA to my AMP and hooking up the Sennheiser HD555's, I was not expecting what came next.

Initial listening to the analogue connections on the Xonar Essence STX was, frankly, incredible. Even on first listen, the card produced a fantastic sound stage. It's fair to say that the difference in the Essence STX is in the analogue connections it provides.

Replaying 'Slam' and the bass started pounding my ears like it should. There was a real detail and depth to the tracks coming out now.

The highs were detailed and clear and the mids concise. The tracks were coming alive on analogue with a very warm relaxing sound that I would not expect from a PC sound card.


Promising an unparallelled sound experience from a PC soundcard using headphones, the Essence STX had a lot to live up to in this area.

Headphone listening definitely matched analogue RCA out for sound. Again the detailing shone through and the card really has the power to run a set of decent headphones properly, you even hear the 'click' of the headphone AMP when it is set to headphone.

Setting the headphone gain to Extra High Gain (+18db for 300-600 Ohms) almost killed both my ears and my fantastic HD555's. Feeling somewhat annoyed that I didn't have a set to compete with the onboard AMP, I grabbed some ancient Technic DJ headphone's I found in my parents attic. These have to be driven by a proper AMP to make any noise at all, so I was hopeful.

What can I say? The Xonar not only managed to power them, but the sound was deep, hard and clear on the Extra High gain setting. The only bad thing is that I had to give the Technics back...

Sound Quality - DVD's


Digital Optical - Dolby Digital Live

Firing up some of my favourite sounding DVD's I set out to see what the Essence STX could do with DVD's in surround mode.

I was surprised to hear that the sound card really produced some of the best surround sound I have ever heard from a sound card. Using SPDIF passthough in Cyberlink PowerDVD and Dolby Digital Live on the soundcard produced a sound-stage that was accurate in it's reproduction and sound truly did fall in the right places throughout.

The Matrix's DTS sound-track was converted by the card into Dolby Digital without too much of a loss in precision. Straight after I listened to it on the Essence STX, I fired up my Panasonic DMP-BD35 Blu Ray player and played The Matrix through that as well and I didn't hear as big a difference as I thought I would, although there was a difference.

The Lord of the Rings - The Two Towers and The Bourne Ultimatum were also dealt with incredibly well and I have to say I was actually fairly impressed with the Dolby Technology on the card, despite initial reservations.

Headphone - Dolby Headphone

Dolby Headphone is fantastic technology that picks up on the audio cues sent through by a multi-channel sound source and converting it for use with a set of headphones.

Again I found myself being very impressed with the sound coming through my headphones. The sound cues were present and the card fools you into thinking the sound really is coming from a centre that you cannot see, as well as rear speakers that aren't present. Pretty impressive stuff really with a depth you won't often hear from headphones, unless you're familiar with the Virtual barbershop Demo.

Dolby Virtual Headphone isn't a direct replacement for proper multi-channel sound, but it comes very close and certainly will enhance your movie experience.

Asus Xonar Essence STX - PCI-E Audiophile Soundcard Page: 8
Sound Quality - Conclusion

The sound quality of the Xonar Essence STX far surpasses any commercially available and viable sound card in it's price category. Barring sound cards costing £200 upwards, the Asus Xonar really is musically the best card you can get at the moment.

At face value, ~£160 seems an expensive proposition, but compare it to it's competitors and you just cannot get a card that sounds this good for music, headphone and DVD listening.

The sound from the Asus Xonar Essence STX is warm and detailed with plenty of depth and oodles of base when you need it. If you've got a set of cans that need driving but don't want to invest (considerably) in a separate Headphone Amp, then I would say you shouldn't look anywhere else.

It has to be said that the Asus Xonar Essence STX also makes your existing compressed music collection sound far superior to how you are hearing it now. The digital output is excellent and on par with the Auzentech X-Fi prelude, sure, but the analogue connections are awesome.

Add to this decent gaming performance and movie sound that is up there with the best in it's price bracket and you have a card that is hard to fault.

I am certainly giving the Asus Xonar Essence STX the prestigious OC3D Best in Class. For Asus's willingness to sacrifice as little as possible on a musically orientated sound card, I am awarding the OC3D Innovation Award too.

The Good
+ Fantastic Analogue Sound
+ Great Feature set
+ Very powerful Headphone AMP
+ Excellent Sound Clarity
+ Great Movie Experience
+ Excellent Dolby headphone Onboard

The Mediocre
* A perceived lack of connectors
* Slightly expensive
* Included extras are a little thin on the ground
* Gaming performance varies

The Bad
- Lack of DTS support?

best in class  innovation

OC3D would like to thank Asus for providing the Sample.

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