Just a note - listening with a set of Goldring DR100s at the moment. It's pretty clear that my amp didn't have the grunt to drive the HD600s to their full potential. Using the Xonar and the Sony amp, these DR100s are answering a few subconcious questions I had about why a few artists didn't sound as good on record as they do live (they do - it's just that I didn't have the equipment to hear it)! Will post a proper impressions thread later. I have a set of DR50s on the way too (don't ask) so we'll see how they do as well.