expert sleepers es8, es9, depending on the type of usb your computer supports
the es8 at least is expandable, not so sure about the es9
es8 is similar sound quality to most usb interfaces - works fine for me
can't comment on the es9 as I don't have one
if you have an ADAT equipped audio interface already - you may also want to take a look at the es3 (and expanders) or the Boredbrain Music Optx (which is new out)
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities