Yes Sir, I thoroughly checked them at home and installed a Known Good Board in each to rule out Connections, Pre-amp etc... Definitely fried something on the Main PC boards.The amps that did not work at your drummer's, did you bring them home and try them again to see if they worked at your house?
The reason I ask is I had a couple SMPS w/class D PA amps that would not respond when plugged into the same circuit branch. They would work fine on their own but as soon as you powered both on the same circuit,,,fail. Doesthe PA at your drummer's have lightweight PA amps?