Conclusion: As the performance graphs show, the ASUS Xonar Essence STX is a high achiever. It blitzed all tests, bar one, where the Xonar Xense got a slight upper hand in frequency response. The Essence STX absolutely obliterated the onboard solution in all tests, which is a good sign considering the asking price. Despite the lack of native EAX support, the Essence STX does surprisingly well in games.
Pros: Crisp audio output, Near flat frequency response, Respectable headphone amp, Very low noise levels on both line-in and line-out, Top-tier components, such as the capacitors, DAC and op-amps, Op-amps are user replaceable, Drivers work flawlessly on Vista and 7, Dolby Headphone works well for movies and games
Cons: Need pricey equipment to appreciate the added quality of sound, EAX emulation isn't quite as good as a native hardware solution, No hotkeys to quickly alter settings in Xonar Audio Center
Summary: Although EAX5 is not supported, Microsoft Vista and sparse title support has mostly nullified the X-Fi API advantage today. The upshot is that the Essence STX is a hell of a good card. Hardcore gamers will still want a real X-Fi, but for folks who are interested in getting the most from their earphones, the Essence STX is your choice.
Pros: Clean and pure sound output and control over headphone impedance.
Excerpt: 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.
Conclusion: The Asus Essence STX is a bit of a strange creature when you think about it. While it’s obviously not being aimed towards the gamer crowd, the inclusion of Dolby Digital Live!, EAX 2.0, OpenAL and DirectSound3D 2.5 actually makes it pretty competitive in the gamer market. If you are one of the growing numbers of gamers who are running through a receiver and big screen LCD or plasma, then the Essence is an option you should seriously consider.