Hey there everyone, I own a solid state amp (Kustom quad100), I want more gain/distortion. It only sounds decent at higher volumes but at low volumes its really crappy for dirty sounds. Can I replace something like diodes/resistors to get more gain? I just need to know what to replace. I have decent enough soldering skills and to do this I think, I just don't know what to change. Enlighten me, please!

Theres a "gain" knob so it should control something, but what is that something? The pot is a 100k pot for the gain knob if that matters. and it says VR1 next to it on the board. Also a "boost" switch that boosts the gain a bit.