FX loop, 2 speaker outs, 4,8,16 ohm impedence selector, channel changing footswitch, pre amp outs, some other stuff(doing this off the top of my head) It has two seperate channels; Rythm: pre-gain, post gain, shared 3-band EQ with lead channel, bright and crunch switches.
It can go from pretty nice cleans around 3-5 on the pre-gain all the way to heavy crunch.
They use Marshalls (one guitarist uses an older Valvestate 8080, and the other uses a 100W AVT 1/2 stack), and have their master volumes cranked to 10.
and by the way by pulling the tubes it doesnt give it the biggest loudness difference, its only a slight change.
I have the 5150 212 combo, and it's loud as a motherphucker as well.