Noob question: I was playing through an Ampeg b2re at a local gc and I saw a gain control, which made me think I could overdrive it. Wrong. I cranked the gain all the way up all I got was a louder clean sound. Not even a hint of dirt. Here's the question: What is the point of having gain control without being able to overdrive the preamp? There has to be some reason, but in my limited experience, volume control on a clean signal is more easily controled by a single gain/master combo. Could someone enlighten me?