The 1622 and the 882 have converters that sound (to me) exactly the same. I believe they're both 20-bit in. Neither device requires a preamp IF and only IF you're using line-level devices. The main design reason for the 1622, according to Digi, is for folks who have samplers, synths, drum machines, etc, to get the audio from their MIDI gear into Tools. The inputs are line-level, so they are useless for mics unless you have preamps. But otherwise they're fine, and gain is adjustable in software between +4 and -10, I think, maybe a little wider...
Get the 882 if you need auxes or you plan to mix in more than stereo when 5.1 comes out. If you don't like the converters, go check out a MOTU 2408. nothing will make you run back to the 882/1622 faster...
