Someone is a little confused here. The Models 3 and 4 came right after the X and were the last to use the S-C amps. The panels in those were raised about 10-12” but they did not have the pedestal base. The Monitor series switched to the transformers and used the pedestal base (which “died” after those models).audionutz, Roy Esposito from Acoustat Service confirmed your determination that they are in fact a pair of The Monitors and were the next version after the X model and before the 3 and 4. Doesn't get me any closer to knowing why they worked properly when I purchased them but didn't when I set them up in my shop.
I am now trying to find the schematic for the MK121-2A interface. Hopefully someone has one and can send me a copy.
I couldn't agree more about short summer. Maine is an amazingly beautiful coastline to travel though.
Roy said they originally came with the tube servo amps.
He said that the interfaces that I have will work just fine with the speakers I have, which are The Monitor that came after the X.