Floris When I switch power, it takes a while for the patch to start running.
That's expected, it should be about 8-10 seconds depending on SD card speed and program.
Floris What would be the handiest way to make these start when visitors enter the room?
You should probably have them always on and only start the patch when visitors enter the room, if that's possible.
Floris And could motion sensors start a patch directly?
If a Bela program is already running, or at least the board is already on, then probably yes.
Floris In the past, I've used simple wireless motion sensors that powered on external audio amps.
something similar could be used to power on the board, I imagine, though you'd have those extra seconds for the bootup time