What the heck happened in 1980?
The exact date varies from brand to brand, but the bottom fell
out of the build quality. Manufacturers sacrificed quality for
production speed and started aiming at the 'general' market instead
of the 'audiophile' market. Analog tuners were replaced
with digital tuners. Discrete output devices were often replaced
with integrated circuits, many of which are no longer available
today. Some pre-1980 models used integrated circuits, and some
post 1980 models were still well built.