Lots of great suggestions for you here, but the one thing to remember (as stated by others) is in the digital world 0db is 0db. Period. Nothing More. A wav will never exceed 0db, regardless of how much you push the gain up in your editor program.
Another question, which I have not seen asked yet: what is between your "mic and other stuff" and the sound card? In most computer-based recording environments, there is a preamp (outboard, in mixer) between the mic and the computer that will provide you additional control in matching/managing levels. Also keep in mind the differences in levels between the consumer (-10db) and pro (+4db) markets. I can run signals from my pro +4db audio interface to my consumer -10db cassette deck and end up with a crappy, distorted recording - even though the meters on the cassette peak at 0db.
I would check what your soundcard is expecting on input (pro or consumer) and compare to what you are providing...
Bill
I've noticed, on some analog recorders, that if you have it set on the Insert mode (for listening to other tracks in order to overdub), the meter of the track you have armed doesn't register until the transport is in record and the tape is moving. It's impossible to set basic record levels that way so it has to be done with the Insert mode off. Maybe there's a similar setting in the digita version?
