To truly enjoy this hobby, I need to learn electronics. Any book recs?

For a few years before his tragic passing in 2019, Roger Modjeski of Music Reference was teaching a class on audio electronics in Berkeley/Oakland. If I was living in the Bay Area then I would definitely have enrolled.

For an introduction to his thinking on amplifier design, search for his talks at the annual Burning Amp Festival, held in San Francisco. There are videos of his hour-long presentations viewable on YouTube, as are those of Nelson Pass.

Bruce Rozenblit's Tubes and Circuits.

Bruce sells /  designs the Transcendence OTL amplifier kits.

I highly recommend Sound Improvement Secrets for Audiophiles. Sounds cheesy but the author, Igor S Popovich, is a highly accomplished amplifier designer. He goes into quite a bit of electrical theory. He even gives plans for cheap DIY cables that he claims outperform the big name fancy ones. 

OP, do you harbor aspirations of designing and/or modifying audio gear? If not, perhaps a solid understanding of acoustics and psychoacoustics would be more beneficial than tackling the electrical engineering, at least from an audio hobbyist or consumer perspective. WRT this, I'd recommend the seminal work by Floyd Toole, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms , now in its 3rd Edition.

Forget about books aimed at audiophiles, like the one by Robert Harley; that’s not technical information, it’s hi-fi consumer advice.

I agree!

Mike