Stereo does not mean two channel.
Go figure!
For all the years I have been immersed in stereophonic sound I have always assumed it meant the opposite of monophonic: one speaker.
Turns out:
stereo
2 of 2adjective
1: of or relating to the seeing of objects in three dimensions
stereo-
before vowels stere-, word-forming element of Greek origin, used from mid-19c. and meaning "solid, firm; three-dimensional;" also, later, "stereophonic," from Greek stereos "solid" (from PIE root *ster- (1) "stiff").
also from mid-19c.
So, stereo means solid: the seeing of objects in three dimensions.
And that turns out to be perfectly accurate for the best HiFi systems from headphones to speakers.
It's just not what I always imagined.
*thanks to our chief engineer, Bob Stadtherr for this revelation