Never had that problem with the 4 SS McIntosh amps I have used/own. Ivanj has a good question - downstream is another possibility if they all used the same speakers. I don't think it is the amps if they are all doing it - it would be way too much coincidence. Good luck!
Why do McIntosh SS amps cut out?
I have known quite a few old SS Mac's. My main amp is a 2205 and I've just picked up a 2505. These, and every other old Mac I've run across seem to have issues with shutting off one or both channels. Switching on and off will usually get it to stay on. Is it just bad switches? It seems more like it is seeing static/noise and going into protection.