Hey guys. Can anyone explain to me what the pros/cons are of amps with a Master volume, or non master volume amps? When did the master volume start showing up in amps, and what is it's purpose? On amps like Mesas, where you have individual volumes for each channel, and then a main output volume that controls the level of the whole amp, what is the best way to get power tube distortion? Cranking the main volume, or the channel volume? Thanks!