FWIW, electronics books teach what things are and how they work and circuit math.
They do not teach you how things break, how things act when things are broken, how to find what’s broken, how to use meters and scopes, how to desolder and solder, etc..,
Electronics tech is a career but the techs now are doing board level replacement on crap and the stuff we like is old school. The parts are obsolete and the “real” world mostly thinks we’re wasting our time on “that old thing”.
It’s not like mechanical DIY at all.
There is no “Stereo Depot” like Home Depot.
It is now a rare hobby/skill/art to own and maintain and repair this stuff.
Because so many people think it should all be dirt cheap at a yard sale or thrift store and work well, there is little demand for vintage repair techs so no reason to get into the business.
The old techs are getting old and fading away.
Many of the hobby techs even around here are not interested in custom repair.
I learned because I wanted to and had stuff I want to keep and enjoy and I hate to see nice stuff go to scrap because no one can fix.
Since I didn’t intend to become a tech, I tended not to invest in tools and parts but over the years it built up. It would take $1000-$2000 to rebuild most of my bench and inventory.
Fixing is a lost skill these days.
I work with techs and EE at SpaceX.
They have no clue how to work on vintage.
So far, I have not met an EE that can fix period.
That’s not what they do.