I plan on using my Nuforce Icon HDP with the Senns 600s I just ordered.
It's a great unit (a bit bright though), serves its purpose well (and for what I want to use it) and seems to drive most headphones out there. Review:
http://www.6moons.com/audioreviews/nuforce14/hdp.html
Right now I have a cheap Audio-Technica turntable connected via RCA, cheapo DVD player (serving as CD player for now) connected through Coaxial and my computer through USB. RCA out is connected to my powered monitors. Everything sounds quite good and does its job well as DAC. You could probably look into this one also if you want an "all-in-one" unit.
Thanks.