And volume. I have a Marshall Plexi half stack and every now and then I'll get a wild hair up my ass and dime it out. It shakes the walls. Standing in the right place though, I can hold a note forever.
Yep, infinite sustain... My old Twin Reverb will make my Les Paul sing like that when I crank it, though I'll be the first to admit its 2x12 cab doesn't have the wall-shaking balls of a Marshall stack. Long ago I played for a while through a Marshall 100-watt head with a pair of 4x12s, and there simply is nothing in the world quite like that experience. Except maybe having a stage backline with 3 such stacks. I saw Blue Cheer at the old Electric Factory in Philly around 1968 -- that was the first time I experienced the power of multiple stacks. It was kinda like seeing God, you're never the same again.