Its that time of year when I revisit one of my old projects and try to improve it. Currently I have a small 12v PA system that has a microphone and I've added an 3.5mm auxiliary input to play music over it. Right now I'm using a 3 point switch to toggle between the two.
This is kind of annoying because I have to switch between the two manually. I'd like to change it so that when the microphone is in use, it automatically switches from the aux input. The microphone attached to the PA system has a toggle switch so I'd like to detect when its pressed and switch it over. I was thinking some sort of relay for this but I'm unsure if I can get a relay that would work at such low currents/voltages (I haven't measured it in a while but I believe its on the order of a few hundred millivolts) and if this would mess up the audio signal. Unfortunately, the microphone is permanently attached and I don't think I'd be able to insert another wire into the mic cord to use as a 12v line for a relay. I'm looking for suggestions on what I could use for this situation.
Here is a quick diagram of what I'm looking to accomplish.