A few years ago I was at a gig with another band, and the bassist needed to use my cab (Ampeg HLF410) since all he could fit in his car was his head and basses. When he plugged his head in, I think it was a 300w Behringer of some sort, and he barely had the volume turned up and it was THUMPING. I have an Ampeg B5R, 500W, and in order to even come close to the volume I have to have the Volume and Master at around 80-90% which just sounds like crap at that point. It sounds great when it's going into a PA, but weak as hell through the cab. So I'm wondering, is there a problem with my head or something else?