Seems as if my left side marshall output along the way has stopped working, this is going to get really really expensive. There is a mono input on the back, and stereo outputs on the back, I just tested it with TS cables and seems like the right side output is the only one working. Great, I never dropped this rack case or smacked it by any means, it literally has just sat there for years. Last time I tested it I believe I had 2 MG cabs with the rack gizmo in mono, and mono input marshall, those were 8ohm and knew to swap the outputs over. Both cabs were working in mono.