Ok so I bought a used amp (Rouge GS-100) It worked for a bit, but now when I turn it on and play, it is very quiet...like abnormally 'I can barely hear anything' quiet. It's quiet UNLESS I turn the volume all the way up(still quiet at this point) and strum real hard. At this point it crackles a bit and then "kicks in" and has normal very loud volume. I can turn the volume back down and play on it normally. It will stay like this for maybe 10-20 minutes, then it dies again. If I repeat the "kick start" process, it will start working again.

What the hell is going on here? Help would be greatly appreciated...I'm playing live on Thursday, and it would suck to be one amp short!