As a quick revisit to this post: my appreciation for this amp has only grown. Here are things that drove me crazy about the Mark V the first time I owned one that I now love:
- Channel 1, Clean mode
- Channel 2, Edge mode
- Channel 2, Crunch mode
- Channel 3, Mark IIC+ mode
I'm using 6L6s btw - which amazes me even more. The only way I could even think about using Channel 2 on my old amp was EL34s.
I really do think that putting the cabinet directly on the floor is one of the biggest factors. IIC+ mode sounds much fuller. I used to think that it didn't have enough gain compared to my other amps but once it has the bass and authority from floor coupling it roars and sounds like a monster.
Edge also sounds much fuller and potent, probably for the same reasons. I'm using a clean boost with Channel 2 but it really sounds great either way. I am stunned. I used to hate Edge.
Crunch is brutal. Sounds fantastic. That never happened with the old amp, either.
FWIW, I play detuned black/speed metal, rock (Foo Fighters/Led Zepplin), and clean, pretty stuff. The Mark V nails them all.