NORMALISE for starts.

Hopefully you got the latest OS on your 808? But NORMALISE in SAMPLE EDIT can really bring up a sample to the 0db mark. Also, there's alot more effects to mask nasty noise. But you really should try to get a clean signal as you record. The Zip drive I think is the main offender most times. So try to keep cables well to the back of the 808, and not draped over top or by the sides. Also, guitar pick ups and certain mic's radiate when near the Zip drive - which is a drag, cause how can you press REC without getting near the 808 (Well, actually you can use a Roland sustain pedal ) And with things like REGION IN/OUT, you can literally trim off noisey silences when the guitar or microphone track is inactive.

But good rule of thumb - keep the 808 as far away from 'acoustic recordings' as possible. Keep 808 away from flourescent lights and TV's (All audio equipment for that matter!) And hopefully your recordings will improve?