ASUS Xonar Essence STX Sound Card

James is back in business and this time he looks at a special Xonar offering from ASUS, essentially a headphone pre-amp for discerning audiophiles.

Manufacturer: ASUS
10 minutes & 59 seconds read time


ASUS Xonar Essence STX Sound Card

The ASUS Xonar line of comprehensive audio solutions has been an impressive option for gamers through to music lovers ever since I took a look at the first Xonar D2 PCI board some time ago. To recap, that was a great board sporting some really good features on top of ASUS' renowned build quality, resulting in a very solid sound card that has proven to be a great building block for their latest range of products.

ASUS Xonar Essence STX Sound Card

Just after Christmas I received a small black box in the mail; this contained one ASUS Xonar Essence STX PCI-Express sound card. The first shock I received was how fast ASUS had managed to get this sample out to myself; this tells me they're excited about the product and to be honest, I am too!

ASUS has taken some truly promising steps with the STX, providing a high-end audio card for the general consumer who might be a headphone lover or simply a music lover, or perhaps both. Now, some of the exciting inclusions here are:

- Burr brown digital to analog converters offering -124db signal to noise ratio which is up 7db from -117db seen on the original xonar I looked at.

- Independent power sources for headphone line in and out insuring signal integrity is maintained always at every stage of the signal path.

- Swappable op amps allowing fine tuning of the cards sound quality to the users liking.

- EMI shielding allows the sensitive analog signal path to kept super clean and noise free at all times.

- New technology in grounding circuitry isolates ultra sensitive analog signal paths from interference and noise.

- Nichicon "fine gold" capacitors offer rich bass and smooth crystal clear high-end.

- Built in headphone pre-amp with software settable gain allowing for high quality headphones to be used without external pre-amp unit.

- Full size gold plated headphone jack and line in for Mic connection.

Glancing over that brief rundown of what the card offers, this will leave audio lovers drooling over what promises to be an absolute god-send for audiophiles.

Now it's time to delve into the goodies and see what contents we get inside.

The Package

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

The packaging designed for the Essence STX is really something to behold. The original Xonar was nicely packaged, but this really takes the cake and features a lovely black box with emboss tiger image adorning the center front and minimalistic styling throughout.

ASUS Xonar Essence STX Sound Card

As seen above, the inside of the front cover features a blueprint of the unit which gives an explanation of the features I mentioned before. Opening the box reveals a stack of three plastic trays containing the Essence card, a driver disk, two pretty posters of the card, manual, test report, gold plated headphone adapter, 1x dual RCA to female stereo mini-jack and 1x coax digital to optical adapter.

ASUS Xonar Essence STX Sound Card

Now, I feel the most impressive inclusion here is the gold bound test report for the card, which is something I've never seen before. Call me a sucker for detail, but I love it; it makes me feel like this is really something ASUS are proud of and not just another sound card, maybe even a concept product of sorts.

Inside the precision test report we have a blurb discussing the symbolic use of the tiger image throughout the product and how it represents the ancient pursuit of perfection combined with the very latest in cutting edge technology. The result? "unprecedented performance", as ASUS puts it.

ASUS Xonar Essence STX Sound Card

Throughout we have several line graphs detailing specific performance results of key areas of the unit. Overall, I feel the way the package has been designed and put together is of a high caliber and I'm sure this reflects the performance of the Essence itself.

ASUS Xonar Essence STX Sound Card

Technical Overview

The Essence features several exciting pieces of technology combined with the use of only the best individual components for the job. At this point I will expand on the brief specifications given earlier.

First up is a professional grade 124db signal-to-noise ratio, or SNR; this is the ratio of the signal to unwanted noise and the higher the better as it simply means the signal is cleaner. ASUS claim that this figure is 64 times superior to onboard solutions currently out there.

Shifting focus to the on-board headphone amp, the Texas Instruments TPA6120A2 headphone driver can support headphones up to 600ohms with less than a tiny 0.001% THD, which again is professional grade performance. Once again, this is great because it means you can drive a great set of headphones with solid clean power, negating the need for an outboard headphone pre-amp.

Next, we have Hyper-Grounding; ASUS' unique circuit grounding technology that uses a multi-layer PCB design in the construction process to separate signal and noise, maintaining utmost signal integrity to the filtering and processing stages.

Now to the isolated analog signal path; the Essence features a gorgeous anodized black EMI shield, as did the stylish Xonar D2. But aside from looking really serious and beautiful, what this shield does is insure the sensitive analog signal path and respective components are kept completely isolated from unwanted noise and electronic interference.

ASUS Xonar Essence STX Sound Card

Located beneath the shield is a copper insulating element that protects the output amplifier stage from the power input and filtering section. This is definitely another professional grade inclusion to the design of the product.

Moving to the digital-to-analog converters, these are always necessary since we cannot perceive a digital signal using our ears; the signal must first be converted to an analog waveform to travel through the air. Now, in order to do this, something called a DAC (Digital to Analog Converter) is used, but as with most anything, there are good and bad ones out there. As such, ASUS has gone with a lovely Burr-Brown PCM 1792A DAC which features a 127db signal-to-noise ratio. Remember, a higher SNR is better.

Technical Overview - Continued

ASUS Xonar Essence STX Sound Card

Nichicon "Fine Gold" professional audio capacitors use the very latest in etching technology to bring forward the very finest bass and treble reproduction. The Essence also features some large purple capacitors known as Os-cons and are made by Sanyo. These can be used for many jobs in the audio world because they are considered high quality filters. These are used in three different places on the Essence PCB.

ASUS Xonar Essence STX Sound Card

To allow further tuning of the Essence, the user can swap and upgrade the boards' operational amplifiers (or op-amps) to units that are of a higher quality, or which possess certain tonal characteristics desired by that specific user.

ASUS Xonar Essence STX Sound Card

Now, with regards to the actual connections featured, I must say firstly that I am very happy not to see any stereo mini-jacks here. Instead, we get lovely full sized gold plated professional level jacks, just as you would imagine the best might have. First are left and right RCA outputs, then we have gorgeous gold plated tip and ring sleeve (TRS) jacks for headphone-out and line-in. Finally, we have a coax/optical S/PDIF output for multiplexed digital surround information from film etc.

ASUS Xonar Essence STX Sound Card

On the rear of the card is a power connector for the headphone amp and on the side of the PCB are internal provisions for aux input from a ROM drive and front panel connection for those with jacks on their cases.


ASUS Xonar Essence STX Sound Card

System requirements for the Essence are as follows:

- One PCI Express 1.0 (or higher) compatible slot for the audio card
- Microsoft Windows Vista (32 or 64bit) / XP (32 or 64bit) / MCE 2005
- Intel Pentium 4 1.4GHz or AMD Athlon 1400 CPU or faster
- 256 MB DRAM system memory
- 60 MB available HDD space for driver installation package
- CD-ROM drive (or DVD-ROM drive) for software installation.
- High-quality headphones, powered analog speakers or a Dolby Digital decoder to enjoy the ultra-high fidelity sounds of the card.

Installing the Essence is simply a matter of locating an empty PCI-Express slot on your motherboard, fixing the card into place and running the drivers in Windows. Both XP and Vista are supported.

I had no problems installing the Essence and everything went smoothly. Attention should be paid here to the quality of the speakers and headphones used with the STX as well as the quality of the audio being played back; they all have a hefty bearing on what performance you will receive from the boards high-end components.

The software interface is very similar to the original Xonar D2 interface which makes the transition a little smoother and it's really not a bad little control center either. I especially like how little the amount of RAM it uses is when compared to others.

ASUS Xonar Essence STX Sound Card

The control center allows setting of all the main features of the Essence along with a handy EQ and environment setting. We also have controls for karaoke, three gain settings for headphones of varying resistance, low frequency crossover, environment settings for gamers, controls for Dolby Headphone, a simple mixer and a graphic readout of the active frequencies in blue at the top. It's very simple, but that's what I like about it and within a couple of minutes I feel most will be quite comfortable in manipulating the various settings of the Essence.


Testing the Xonar Essence STX

Now that we have a good idea of what this board is all about and we have had a look at the many different features and components involved, it's time to discuss how it sounds. This particular model of the Xonar is aimed fair and square at the music listener and I will reflect this in my testing discussion.

ASUS Xonar Essence STX Sound Card

There are two main areas within which to conduct the musical testing of the Essence and they are the analog signal path and the digital signal path. It's also important to remember that analog signal integrity is the key here and that many of the design elements were put in place to maintain purity of the analog signal.

First we'll cover the performance of the headphone-out using a pair of Sennheiser HD433 headphones running at the intermediate gain level of around 8db.I used a wide variety of music as I usually do to test the various aspects of performance.

I found the sound quality being delivered to my Sennheiser's (of which might I add are far from pricey) to be of a very high quality, capturing fantastic percussion harmonics and possessing an overall warmness not unlike my very old Yamaha natural sound amp.

ASUS Xonar Essence STX Sound Card

I also immediately noticed how musical the Essence sounded, meaning that lots of transient sounds were present making for a very smooth dynamic feel to the sound without any harsh digital roughness. The high end is very crisp and present, but not too harsh or over done. Vocals come through the mix very well and feel warm with lots of character.

With Dolby headphone turned on, a 3D environment is created from a stereo signal and depending on what is being listened to it can work well or sound very heavy on the low end, leading to a very garbled sound. I guess if you're the sort that likes to 'add' to their music, DHP will be great; for everyone else, though, I don't think it will be hard to avoid.

There are three different gain settings for the headphone pre-amp with 0db gain, 8db gain and 16db gain, which should be sufficient in covering all headphones, great and small. I found 8db to be perfect for my Sennheisers.

ASUS Xonar Essence STX Sound Card

For testing of the digital out, I used an optical cable along with the provided adapter to connect to my JVC receiver and with a pair of bookshelf speakers. The sample rate was set to 48 KHz because that is the receivers limit.

I immediately noticed a marked improvement over the original Xonar's digital out which I had being using in days leading up to this testing. Many of the aforementioned benefits felt when testing with the headphone output are also present here, but not to the full extent as this card is built to do analog first and foremost and also because the on-board pre-amp is not being used for the digital output stage.

Testing - Continued

Put simply, the Essence sounds great through its digital out and I would imagine even better when the sample rate goes up to 192 KHz.

At the end of this review I will include images of the test results run by ASUS in their labs using their $27,000 audio precision testing equipment, for those interested in viewing them. I thought it better to do it this way rather than explain each parameter, otherwise this review could suddenly span out 10 fold.

ASUS Xonar Essence STX Sound Card

The Essence STX features a very nice signal-to-noise ratio, total harmonic distortion, crosstalk, frequency response and other impressive results. And without delving into the science behind it, I'll simply say from the instant you listen for the first time you can really hear these factors come into play in creating such an impressive sound stage.

Looking back, we have come so far since I had my first Sound Blaster Live! upwards of seven years ago and the leaps in sound quality have been pronounced since then.

Testing - Performance in Movies and Games

Focusing on the performance with movies, as the Essence is not intended for decoding of movie soundtracks, it doesn't feature any onboard decoders for such use. Instead, you must pass the digital data from the films soundtrack through the Essence' coax digital-out to an outboard decoder like a home theater receiver to hear the soundtrack correctly. Another way would be to use headphones with Dolby Headphone to listen to movies using the on-board pre-amp. Either way works fine and will allow a fine high-fidelity reproduction of the films soundtrack.

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

Performance with games is not what I would call a primary concern of the Essence. However, it does support gaming through the latest Directsound 3D algorithms, which is better than having no support for gamers. But if you're a gamer first and foremost then I would not imagine you would have too much interest in the Essence anyway. I'm not going to go into great detail here, but yes, if you wish to use a board like this to game, you can up-mix using Dolby Live and Dolby Pro Logic 2x to create a phantom surround image. Of course, Dolby Headphone is also there for the same reason.

Final Thoughts

The Essence STX is not only a great member of the Xonar family, it's the best sounding board I've ever heard in this price bracket. I'm sure it will leave a lasting impression in the minds of competitors and may even send a few back to the chalk boards, scratching their heads. But most of all, I think it's the age old cliche; 'attention to detail' that lifts the STX above the crowd with some really nice components chosen and a very high degree of build quality, as with all ASUS products.

The choice of high quality Nichicon "Fine Gold" professional audio capacitors as well as Sanyo Os-con filters alongside their custom EMI shield and chipset allow the STX to stand out well. The software is not bloat ware and handles the job easily, allowing for quick and decisive control of important features. I really struggle to fault this little control center because it just seems to work!

ASUS Xonar Essence STX Sound Card

So, is this board worth a few hundred down? Well, yes; simply put, it is very much so. However, that doesn't mean it's for everyone, because it is definitely not. For the price of this alone you could be looking at a CPU/motherboard upgrade, so it becomes a question about which direction you want your money pointing at. How important is 'the best' sound when your CPU is still from the Pentium family or you're still using an AGP graphics port? For me it's easy, but for many out there the decision is not quite as easy and can be daunting if uninformed.

Sound cards can be tricky to choose, but remember that you don't have to rush your choice; be patient and buy something with the features you need personally and leave it at that. I do, however, urge those looking for the most exquisite stereo audio performance to consider the Essence STX in their new PCs or Home Theater PCs; maybe even a jukebox PC.

As promised for those interested, here are some snaps from ASUS' test report on the Essence STX, showing how well it performs in key areas.

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

ASUS Xonar Essence STX Sound Card

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James has been interested in all types of audio for the last 6 years or so. He began as a moderator at the very well respected 3dsoundsurge forums. From there he was offered a spot testing Philips Acoustic Edge sound cards in beta form. He then began writing for Hardavenue, which lasted about three years before it was acquired by Tweak Town Pty Ltd. For the past nine months, James has attended the SAE (School of Audio Engineering) institute in South Melbourne, Australia. He handles all of our sound card and speaker product reviews with very knowledgeable and in-depth analysis.

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