I have a couple (10 or so) microphone XLR inputs that goes into my analog mixer Allen & Heath PA20. The problem is that the channel inputs don't have a signal LED that lights up when someone speaks. So I have to rely on a stage hand to communicate to me, the currently used microphone or I have to individually check the PFL levels of the channel.
I am looking for a cheapest way to fix the issue. Either a device that I can use as a bridge between my microphones and the mixer which tells me the currently spoken into microphone.
Or a custom solution like attaching a Raspberry Pi in between and using a simple algorithm to figure out the active microphone (maybe getting the max level from all inputs and then using thresholding on the max level)