Dave Smith Instruments SYNTHESIZERS

So I just got an evolver and it's great. However, it might be my
imagination, but I feel like I lose something in the A/D conversion on
my SB live when I record. It's weird because it sounds fine going
through the line in to the line out of the soundcard (but maybe that
circuitry bypasses A/D conversion??). 

Anyone have any insights on this issue? What differentiates a cheap
A/D from a good one and how does the SB live stack up? (if it sucks,
tell me what about it makes it suck). 

Austin