The biggest shock to me is finding how sound quality has regressed in many respects from where it was decades ago. For example, many of these very best sounding recordings were made long in the past. For example, originally pressings of Brubeck’s “Take Five” (1959) sound better than the vast majority of modern recordings; the same with Ellington’s “Blues in Orbit.’ Mercury and RCA recordings from the 1960’s are also astoundingly good. As for gear, many speakers and drivers from the past are better than what are made today. Show me midrange drivers better than compression drivers from Western Electric, Racon, and YL. There are fantastic amps from more than 70 years ago that are killer good (e.g. Western Electric 124 and 133).