FWIW, using my RME Digiface (and the 96/8 PAD when I owned it), I found the sound considerably better in ASIO. It has been awhile since I checked, though. It was a big enough difference that I wondered if the data integrity was being maintained. Perhaps it was something else, but I did in fact hear a rather substantial difference.
Plus- in most programs, the monitoring choices in ASIO are better anyways...
--Ben