If you're a tube-miser, you can install the C4S boards in a mirror fashion, as you only use one triode section in each driver tube with it. Adds about 15 min. to the short process. Theory is then you can swap the tubes in the monoblocks after one side starts to go...pins 4,5,&9 are heater, then pins 1,2, and 3 correspond to pins 6,7,&8 (i.e., the triodes run in opposite directions in the tubes). Probably not a big deal either way...

Glad to hear your experimenting...

Matts