I just bought a GB Streamliner 600 & an Uber Quad cab to go with it. I just finished trying the amp out and it doesn't seem that loud. This is the biggest amp in wattage and physical size that I've ever owned. I've had small practice combos sound louder than this! I plan on calling Genz this upcoming week, but I wanted to see if anyone here had any advice for me. On this particular amp does the preamp gain and volume have more to do with amp volume than the master volume? By the way, I'm using a G&L SB-1 (P-Bass) with flatwounds and George L's instrument cable. Thanks in advance for any and all help.