I've posted before that my MC50 is so loud I haven't even used it yet above 1/3 even with my band (this is driven by a Fyd preamp on 5 into an E120). You wrote:
>> I set the Mc50 at 12 and also in its maxed out position (5 o'clock) and really did not think it was very loud. Certainly not as loud as if I was driving the tubes [of the Blues Deluxe].
Having also previously owned a Blues Deluxe, there is no doubt to me your MC50 is not working properly. When I bought mine, I forwarded it on for servicing before I even turned it on. 40 years wreaks havoc on caps and sometimes other components.
When and where did you last service yours?
"For me, I think the only danger is being too much in love with guitar playing. The music is the most important thing, and the guitar is only the instrument." Jerry Garcia