Thanks for the informative reply! Your recommendation is one of the reasons I decided on the 600. Anyways, the things you said confirmed some old fears of mine that I've been relegating to the back of my mind; namely, that I need a quality interface. If I did stick with the Ozonic, would it be worth it to put a good headphone amp after the headphone output? I realize this wouldn't improve the DAC, but would it be enough to get reasonably good, neutral sound from the 600s? Mind, this is mainly for a project studio recording my own stuff and occasionally doing production work for a professional radio station. Cheers!