On the MkII the switch is accessed via a small rectangular slot found on the bottom plate between the tube sockets. On the original the switch is located at the same place, however the bottom plate needs to be removed as it lacks the slot. According to the original owners manual this must be done by a service tech. I believe, with care one could accomplish the task themselves.
Lucky for me I own the MKII. If I wanted to rum a pair as mono amps I would want the pair to be of the same edition as sonic improvements have been made, in particular between the original and the MKII.
Lucky for me I own the MKII. If I wanted to rum a pair as mono amps I would want the pair to be of the same edition as sonic improvements have been made, in particular between the original and the MKII.