My first experience with stereo was in the late fifties when two local radio stations each broadcast one of the two stereo tracks. You had to have two radios, one on either side of you, to get the experience.
Later in life, my favorite stereo system looked like a pair of cushioned black and white dice rolled into the living room. One die was a speaker and record storage; the other was the turntable. The cubes were maybe two feet to a side and rolled around on rollers. I used to get hammered and lie down between them and listen to Richard Burton doing Hamlet.
I have heard an experimental stereo recording of the Count Basie Orchestra made around 1930. The quality was astoundingly good.
I was amazed as a young adult to learn how FM stereo worked.
They transmit an A+B signal, and A-B subchannel. The receiver does a little quadratic equation and separates them out into A and B.
And I was so certain that algebra was useless.