I'm involved in a jam session, among some friends or workmates, on a stage in a warm wooden room, like a church. There is a violin or cello laying flat on its back, and I scrape a pick on it to make a clicky percussive sound. People seem to like it, but it's not loud enough. It's not plugged in.

Somebody tells me to grab one of the things out of that bag; there is a whole bag full of these littler bag, each one with a pair of things in it that look like earbuds, but without wires. They pairs of wireless receiver/transmitters. I plug one into the violin, and the other into the mixing console.

I wonder briefly how they connect to each other, with other such devices in the system, and then realize that's probably why they are in pairs; they are probably permanently matched to each other.