So hopefully one of you guys can help me out here... I just bought a Crate G80XL for 60 bucks... I knew there'd be a problem with it, as that seemed like a ridiculously low price for that amp. So the problem is this; At a lower volume, the amp sounds fine. The louder I crank it, I start to get these "pops" that sound very similar to the pop it makes when I power the unit on.  It seems like the more bass I have, the worse the pops get...  I already cleaned out all the pots with contact cleaner... I'm thinkin it may be the power supply caps, but I'm not sure... Any suggestions?