Summary and Conclusion
The Asus Xonar Essence STX is marketed as an Audiophile's sound card. That being said, we could do without some of the non-essential bells and whistles. An audiophile will never be satisfied with the stock EQ presets and there are plenty. The rotating surround sound is more a novelty than anything else. The line out left and right slides on the mixer could use a link that allows them to be moved together so both do not have to be adjusted independently. The only need we see for this is that on some systems there is a higher output on the left channel which could be accommodated by circular gain controls at the top of the slides. We could do without the karaoke section as well. We understand most of these driver features are carried over from other Xonar sound cards but Asus is setting a new standard here that merits a refresh of feature controls, and perhaps a nice packaging of encoders and audio applications.
Finally, one thing we noticed while testing is a clicking sound upon booting, shutting down and switching inputs on the card. Don't be alarmed, this is just the sound of an internal switch that resets the circuits to prevent bleed over from capacitor voltage.
For the price of the Asus Xonar Essence STX ($199.00), you expect a lot and frankly it exceeds expectations. It is a product that appeals to those demanding the highest level of fidelity. This card is the first of its type marketed to consumers that produces SNR levels that will please even the most demanding audiophile. You would spend much more than the price of this card, to achieve the same performance in a professional series audio interface.