Okay here's the dealio, and I think this has been plaguing me for a while now and I didn't even realize it was doing it (Causing) it at full band practice levels.
I quit using the fbv shortboard mkii with the Vetta because I picked up the mk i recently and like it better. Better switches/better screen blah blah.
So the issue is ( I just found out) is just the slightest touch of the gas pedal and it drops the volume level.
Then when you change to a different patch within the same bank the volume goes back to normal.
So last night I shut off the vol pedal for both amps in the effect control setup menu of the amp. Now everything works perfect, except no volume pedal lol.
So I turned them all back on and set the minimum to 55% on all and saved thinking that might work cool as a volume boost method as I'd leave it in the heel position and then push to toe position for leads. Once again this works great......Except for the fact that that slight pressure on the pedal or switching between the patches changes the volume level again......Arggggh