Asus Xonar Essence STX 124 dB SNR / Headphone AMP Card

This is a card designed and marketed to the audiophile audience. It should be understood from the get-go that this is NOT a card for gamers and falls fairly short of the EAX processing capabilities of any card from the SoundBlaster lineup. Where this card does excel at is music reproduction, and that is what we're going to talk about now.

With names like Burr-Brown, Cirrus Logic and Texas Instruments adorning the spec sheet, aural pleasure seekers will undoubtedly take notice and start to grasp the capabilities of this humble internal soundcard. It connects to the mobo via a PCIe-1x slot, which provides the bandwidth necessary for the card to outsource EAX processing (beyond the natively-supported 2.0 level) to the CPU. At the rear of the card, you get a 6.3mm jack for headphones, another of the same for mic input (a 3.5mm -> 6.3mm adapter comes with the card), stereo RCA jacks and a S/PDIF jack. Note the absence of support for any hardware that goes beyond stereo.

What stands out the most about the card (especially if you pin up the gigantic poster featuring its likeness that comes with the card) is the beautiful EMI shield. As functional as it is visually appealing, this comes as a boon to those who demand uncompromising sound from the noisy environment of a PC. To take things a step further, Asus engineers have wisely opted to have the card powered directly from the noise-free PSU via 4-pin molex. And then you add a touch of 124dB signal-noise ratio output, and any listener is sure to fully understand the meaning of the phrase: silence is golden.

As these impressive specs add up, it becomes apparent this card is designed primarily for use with headphones. When you consider the built-in amp that drives cans with impedance up to 600 Ohms, it should be understood that this card is designed primarily for use with very good headphones. As such, low-impedance phones will be a poor choice. Using 32Ohm-impedance cans, I did notice a touch of distortion in the treble and a dubious quality in the bass (the latter would more appropriately be attributed to the headphones). Boosting the impedance on the same set of cans to the 300-600Ohm range and cranking up the amp gain had the treble ringing with clarity and, as is to be expected, vastly improved the energy being pumped into the low frequencies.

If the purchase of this soundcard happens to put high-impedance cans out of your budget, worry not, it's cheap and easy to build a resistor adapter (google) that will not only make the most of your STX but also very likely the most of your headphones as well. Let's move on

...to OpAmps! With great foresight, Asus has mitigated the need for anyone to take a soldering iron to the card by using sockets for the OpAmps instead of soldering them directly to the PCB. This encourages any user dissatisfied with the sound of the JRC 2114Ds that come standard to try something else out, and I can attest that the change has a remarkable affect on the sound signature. I have no doubt there is a unique OpAmp out there to bring the most out of each genre of music, and with the low cost of IC OpAmps and ease of swapping it's within the reach of all users to take fine-tuning to the extreme and really get their money's worth.

After all the praise, I'd like to end with what the card lacks and that is support from Asus. Contrasting the quality of the hardware and ability to customize it is horrible software, complete with a very bland driver and a Creative-esque "Audio Center" that allows you to select "effects" that no audiophile would ever in their right mind use. The only useful functions of the Audio Center is the 10-slider EQ and box that lets you select gain level. The "Dolby" branded effects are handy in making movies sound better but have absolutely no practical use where music is concerned. To compound matters, Asus reps don't respond to requests for support via the manufacturer's own forums. Fortunately for us STX owners, the 3rd-party UNi Xonar drivers (google) pick up the slack and offer all that you'd need for a Windows install, and ALSA provides support for all the functions of the card for Linux.

So, to conclude, I'd like to say that the card has exceeded my expectations. The JRC2114D OpAmps provide a bass-heavy but well-balanced soundscape out of the box and the ability to swap OpAmps pretty much places the card up any audiophile's alley. The only thing left is to choose your headphones wisely and prepare to enjoy the sounds of your favorite tunes.

In my view, the STX is a bit overrated because every review you read out there makes it perfect. This was not my experience and I learned it the hard way. I purchased this card after seeing it recommended everywhere. The reviews were stellar and I pulled the trigger. The card arrived and I was impressed by the build quality. Asus did a nice job. First thing I noticed is that this thing is huge. I had to re-arrange all my components because the Rampage II Extreme has a very tall heatsink which blocks the STX if you try to use the first PCI-EX.

I installed the card and the control centre is very straight forward to use. All the necessary options are in front of you. I have to give this a huge plus because on Creative products you have the menu, left right, sub menu mentality which gets annoying sometimes. Whilst straight forward, Asus software seems a bit rudimentary. Creative's level of control on the card is better so this is where I started to notice that my Titanium X-FI, at the time, had more features. So I plugged in my headphones and speakers in the STX. I started testing with high quality flacs via ASIO and I noticed a tendency towards the mid range. This is not a problem because you can correct the sound to your desire... or so I thought. The card has a very FLAT sound and making the assumption that this is how the sound engineer wanted it to sound is wrong as the XONAR STX is not what they used to record. Furthermore, Celine Dion and Madonna use different equipment so even at the studio level you have discrepancies and sound processing limitations.

I tried to adjust the sound to add some bass and some treble but apart from the equaliser there was no other way. Creative offers independent bass and treble control. The STX does not and the only way to change the way the card sounds is to change the headphone impedance. This only amplifies the original FLAT sound. So this card is not perfect as many would make it. It lacks proper frequency separation and independent frequency customisation.

Why did I rate it 3.5 / 5? Well, I am amazed at how clear the signal is. You increase the volume and the level of distortions is non-existent. Compared to my Titanium cards (both normal and HD) where I increase the volume and everything starts to distort the STX is sublime in this regard. Also, you can switch between the heaphones and speakers from a simple button. With my Titanium HD, I have to always go behind my PC and plug / unplug things. Skype Audio is great because of the AMP associated with the microphone. The STX is a very good card if you prefer sound with a lot of mids. If you are like me and want full control on each frequency spectrum, then this card is not for you.