what bit rate are you recording at, you should not need a compressor for gain staging, a compressor is to even out dynamics.
If you aren't recording at 24 bit, that is your next step- in your other thread I reccomended a new interface, definatelyt look for that, your soundcard is probably crapping up your signal.
I used to record 16 bit and life got so much better with 24 bit, it essetnially raises the headroom (max dynamic range) so you can record a stronger signal without digital clip, and makes it less a question of precision and more about what sounds good.
Daav