I had what I remember was a 67 50w Marshall (JMP, plexi front, small box, etc) and it sounded great as a bass amp. I used to plug into the 2nd input top, which was rounder than channel one. I have to give another nod to the RnB classic amp for bass - the Showman. I did once or twice in a studio plug into a Twin as well, but that is a Showman guts wise.