ASUS Xonar U3 USB Audio Card Review @ Neoseeker
 

ASUS tackles lackluster sound quality in note- and netbooks with the Xonar U3, a small USB audio card with a built-in headphone amplifier. There's convenience in the form of a portable optical output tucked into this small shell, but we put the U3 to the test to see how it compares to typical onboard audio solutions.

http://www.neoseeker.com/Articles/Ha...asus_xonar_u3/