I have the marshall valvestate 100. Channel volume and master volume. Whats the difference between the channel volume on 1 and master on 10, compared to the channel on 10 and master on 1? is there a difference. And what do you mean by pre and post amp? Could you add the 'gain' to the sound via a effects pedal instead thus reducing break up? beacuse the pickups wouldnt be picking up that when you are playing?