No introduction HRH. 2 channel high or low. Actually acute or darker. Advantage can split the two channels to have a broader spectrum. Essential as everything plays guitar volume. If the amp saturates at full load (to, from 5/6) it is possible to return to a more crunchy or light playing on the volume knob on the guitar. This is what some call "the magic of plexi). However careful here not master volume. So either you're going to blow your eardrums will bleed fast enough either buy an attenuator to enjoy this monster. The fact is the true sound of AC / DC. (5/6 there is).