After a lot of research and demoing I have just invested in a CAD 1543 mkII for my pro listening-studio (used for choosing and checking audio files for record companies). It is a classic r2r using a number of the old Philips 1543 chips, and is the most musical dac I have personally heard at any price point. I love its pure simplicity: one USB input only, no filters to mess about with, no external power cord to worry about, one pair of rca outputs, short signal paths, and a well-designed power supply.
Ideally of course you do need to hear your shortlisted DACs in your own system as system synergy is key.