Techgage.com posted an exhaustive look at ASUS' latest high-end sound card... devoted to headphones users A quote from the article:

The majority of the high-end PC audio cards targeted at enthusiasts typically focus on multi-channel performance, with a variety of decoding modes, DSP enhancements, and other features tossed in. The Xonar Essence STX from ASUS has an entirely different focus - delivering audiophile-quality stereo output.

>> ASUS Xonar Essence STX Review