Thought of that but it doesn't seem very professional.
Unless the code is such that you have to kill everything except for one mic to make emergency announcements, then that IS the way to do it. Matter of fact the code may require it to be done by killing power. They do make sub-panels with an internal contactor, mainly used for remote turn-on but also for this purpose. Good for multiple circuits feeding large amps etc but I think it would be overkill for just one.
-Hal
