preamp into Mark IV effects loop question

[boogietone]

On my MKIV "A", the normal loop is the loop on the left as viewed from the rear of the amp. The one on the right is footswitchable. On my amp, both loops are labeled as such. Can't help you with routing your JMP-1, but it sounds really intriguing. You still liking those KT77's?

 

[eltrain858]

rabies, you're reading about a IVA when you must have a B. the A's had the two loops, the B's have one footswitchable loop with stereo returns.

as far as i understand running your jmp in mono/stereo into the effects returns won't change your tone a bit, since the left return feeds the satellite out and only the right goes to the power section of your amp.