I played around with it a little today. I thought that the gain knob on my line 6 spider II didn't do anything on the clean channel, so I kept it all the way down.. turns out it acts as an extra tone knob of some sort, perhaps a presence control? I dunno, but when I turned it up it warmed my sound right up! of course, this is just for this one amp, I gotta figure how to fix the same problem with my other amp now, but that one the problem wasn't as bad.