I share the frustrations with modern gear that
@SoundMann described in his first post (although I wouldn’t have described them quite as emphatically). However, I don’t think feedback is a major factor in what has gone wrong with modern hifi. The following factors deserve higher blame in my opinion:
Speakers with small woofers, narrow cabinets, metal cone drivers, spiked feet, and crossovers with film caps. Put these together and you get a lean, bright and edgy sound. Give me any day a 15” paper cone woofer with Alnico magnet in a wide cabinet.
Electronics with metal film resistors and film caps. Most (not all) sound bright and lean and give an artificial hyped sound.
Cables with rhodium connectors. Ditto with above.