Get this reference recordings if you can. http://www.amazon.com/XLO-Reference-Test-Burn-In/dp/B0000015AL   I use track 9 (System Burn-In) and just put it on a constant repeat.

@wje: Thanks for the long reply. But did you actually mean to look at the "Asus Essence One" with the Muses chip?  or the the Asus Essence STX, they are two different things, one being a USB-DAC and the later being a internal PCIe card?

Hi, I'm about to build a new PC, and can't decide if I should just reuse an old Asus Xonar DG soundcard or should I get a new USB-DAC.   I use my soundcard with headphones (AKG701, Audio Technica M50's, Samson SR850), and most of my listening is to music, but I do occasionally dabble in a...