XLR:
Originally manufactured as the Cannon X series, by 1950 a locking mechanism was added (Cannon XL)[2] and by 1955[2] a version surrounding the female contacts with a synthetic rubber polychloroprene insulation using the part number prefix XLR.[3][4] There was also an XLP series which used a hard plastic insulation, but was otherwise the same.[2] ITT Cannon originally manufactured XLR connectors in two locations Kanagawa, Japan and Melbourne, Australia. The Australian operation was sold to Alcatel Components in 1992 and then acquired by Amphenol in 1998. ITT Cannon continues to manufacture XLR connectors in Japan.
Chinch (RCA):
The name RCA derives from the Radio Corporation of America, which introduced the design by the early 1940s for internal connection of the pickup to the chassis in home radio-phonograph consoles. It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible.
RCA connectors began to replace the older quarter-inch phone connectors for many other applications in the consumer audio world when component high-fidelity systems started becoming popular in the 1950s. However, quarter-inch phone connectors are still common in professional audio, while miniature phone connectors (3.5 mm) predominated in personal stereo systems.
I'm quite old and have not used XLR in my life, RCA however has been a standard even in communist countries I come from (but to be fully truthful, yes, I do remember having to plug 1.5 metre sized speakers with separate + and - cables, so you're right, there exist speakers that have separate input for each 1/4th of a stereo cable, I am still to see any PC speakers that have this setup though, and if HDMI vs SPDIF differs on them will be surprised as they just forward differences in voltage)
