I just bought a used AC30CC2x. I'm lovin' the the amp, but I've noticed that when I'm not playing, there seems to be a slight 'put-put/static' sound. When I play clean, the amp sounds fine, but when I use my fulldrive or xotic bb pedal there seems to be an annoying buzz/fuzzy sound. Does this sound like a bad tube issue? I sure hope it is. If so, any recommendations on what to use?