Alright then...
My tech has the amp opened up again, as the volume doesn't seem to be what it should.
Apparently the signal travels from several points between the power section and the preamp, and the preamp is quite complicated.
At this point the gain on the preamp has to be all the way up to get even moderately significant volume. The model I have, the MK IV, doesn't have a schematic or any kind of plan available, so I'm starting to dig in and see if I can talk to any of the people who had a hand in the early designs.
So far my tech has been essentially reverse-engineering his way through the amp, and it's exhaustive.
I'd be very interested in hearing about any sources of first-hand info about the MK IV'S design.
Thanks!
It's off to Ashdown...