FYI.. the Mesa Carbine (M6/M9) is not really voiced for overdrive, and neither is the Shuttle 6/9. The Mesa M6 will most likely bury the Shuttle 9 in low end and volume, and the M9 will massively squash it... those heads are like freaks of nature volume and low-end wise. If you are looking for overdrive capability, the Shuttle Max heads have that capability, as does the Mesa BB750.
I should clarify. I'm not looking for massive amounts of overdrive at all, but can you dial in a noticeable amount of tube grind/overdrive?
Great, now you have me leaning toward an M9 again, but I ain't gots no money...

