I have the JCM 900 100w Dual Reverb Hi Gain head, model 4100. I don't have the 1960A cab yet. The cab I currently have is a MG412BCF 4X12, 120W RMS and 8 Ohm impedance.

With the JCM 900 head impedance set at 8 ohms and the mode switch set to High will this function correctly and not cause any damage? It should be ok as long as the impedance is the same on both head and cab, correct?

I need to use this set up until I can buy the 1960 cab. Also, how would I connect two 8 ohm cabs? The total cab impedance would be 4ohm, but I believe the 4 ohm switch on the head is for combos only.