For you folks that run the Mark V head into a single JCM 4X12 cab, which input are you plugging into in the back of the 900, and where's the switch set to? I've been using my mesa 2x12 recto cab, but now that I'm playing in a second band, I have an option to use the JCM cab at the other place. This way, I don't have to haul my 2x12 back and forth.