Alright, so I have a 5-string Spector Rebop bass, a Carvin 1x15 cab, and an Ampeg 4x10 cab. I'm running a GK goldline 500 head, which I hate with the fiery passion of a thousand burning suns. A buddy of mine offered me a QSC power amp that can power the cabs better, but now I need a preamp...