Hi Dave ,
I didnt lift the heatsink on the new unit ,but as far as I can see the pads for the extra op amps are still there, everything runs in parrallel from the 3002 ,power ,inputs and outputs ,so I think that should be fine . Some other differences I noticed were U302 ,which was unpopulated on the 6600 board is now gone . Also the op amp for the input has been moved back from its original position ,I'll get some proper daylit closeups of the boards tomorrow and post them and I can nip around with the bleeper and see if the pin config on the STM tallys with the 6600.