Welcome!
Seems like you've been out of it for a long time. Much has changed. CD's have come and gone, replaced with something called the internet. Music is streamed now. Subscription services like Tidal or Qobuz offer millions of CD quality albums and higher resolution formatted music can be downloaded. Dedicated audio servers exist and freestanding DAC's (digital analog converters) are everywhere (even in receivers and loudspeakers). Vinyl has made a bit of a rebound and tube gear is still around. Much of the solid state amplification has gone to highly efficient class D. More and more loudspeakers have become active (built in amps, one per driver) for better performance.
Floyd Toole developed a testing method to accurately predict loudspeaker performance and has found that the inherent in-room bass peaks/dips can be largely addressed with use of 4 carefully positioned subwoofers. Room size/shape and setup has gotten more attention as had various room treatments. And now there are several electronic measurement/equalization products available to provide the final touch to loudspeaker/room response.
Overall there's never been a better time to get into (or back into) audio as value is very high (especially with streaming services) and convenience reigns supreme. But bricks and mortar retailing has taken a big hit, now-a-days most shopping (research) is done online.
