THe VT1 has input level, gain and output level. The input (i read) is to compensate for output level of the Bass, active/passive etc. I have that pushed past noon, the gain similar (just a touch of break up) and the output cranked), but to answer your questions, the Sumo could be pushed a lot harder. The pre amp out from my Thunderfunk drives the Sumo much harder, but I still see the same issue where Cabs are overloaded before I reach volume I need to cover the Band. The thunderfunk, needless to say is ample. It drives the same speakers to easily loud enough without any complaints from the cabs