If you're are used to the Dynaudio BM15a, I'd try the BM6aII or a second hand mkI.
Regarding a converter/audio interface, I'd advice the RME Fireface UCX. I own and
use the UC and it's really nice. The UCX is a recent update and can also be used
on an iPad(2,3,4) (for a mobile setup, it could be handy).
But it largely depends on your budget..
Check out the Prism Sound interfaces. I use the Orpheus unit myself and it sounds amazing. They now make a half sized Orpheus called the Lyra, that would be my pick for you if you're after the best D/A - http://www.prismsound.com/music_recording/products_subs/lyra/lyra_home.php