I'm staring a collection of vintage loudspeakers. It's interesting to note that most old radios had extension speaker sockets. I remember my grandfather having extension speakers in every room, all switchable from the radio in the dining room. He even had a speaker in the garage for when he was working out there. I suppose it was a lot cheaper than buying a radio for every room in the house. Many speaker cabinets were fitted with a volume control, which was either a wire-would pot or switchable resistors.