Here's the deal: My only amp set-up for the last 20 years has been a Carvin PB 500 with matching Carvin 4x10 and 1x15 cabs. Right now I am using the Carvin head and 1x15 for rehearsal and the 4x10 cab with a GK Backline 600 head for solo practice. I have been offered an SWR 350x in trade for a bass I have. We play 90s rock. My question is, I guess, is the SWR 350x a substantial upgrade over my other two heads? I've never played through one and was just curious how it ranks among these other two heads I have.