ASUS Xonar U7 Review @ Vortez
 

Till recently, the only available audio processing via USB from the Xonar camp was the lightweight U3, or the ultra-high end Xonar Essence DACs that require the sale of essential body parts and organs to afford. The Xonar U7 offers 7.1 surround sound, S/PDIF out and a headphone amp for maximum versatility in a lightweight and compact case.

http://www.vortez.net/review.php?id=816