Hi, I own a SWR 100 watt LA-15 combo amp and at band practice it seems to let off a distorted, buzz like sound just when I play notes. I'm guessing its my amp because I've tried adjusting everything on my bass and it [the buzz] still haunts me. I don't know what it is, I don't think its too loud volume, because I've tried numerous EQ and master volume settings and the buzz is still there. Also, my amp's bottom is uneven, so it tends to rock back and forth. I noticed when I sit on my amp the buzz disappears. Strange... could someone possibly point out what is wrong?