I just bought a Fender 50s Players strat and a peavey C30. They are both awesome. The C30 sounds amazing!!! the strat kicks ass. But i have an issue w/ the C30. Every time i push it past 6 or 7 on either chanel its makes a nasty scraping sound if i use the low E string(6th). WTF is wrong. Could it be the cable? tubes? speaker? It sucks because i like the amp and i got it for an awesome price $340 "new" form guitarcenter. Its the tweed version.

Help Guys? Should i just take it back the Guitar Center. I got 30 days to take it back...maybe ill take it back and save up for a ceriatone 18w.
it could be tube rattle, the C30 tends to do that at higher volumes. try pressing against the tubes lightly with a pencil eraser or something when you play. if that causes the noise to stop, then thats your problem. they have tube retainers on ebay for fairly cheap, so thats a simple fix to that problem.