20 Year Old Amplifiers compared to 2017

Amplifier technology reached maturity in the seventies, when output transformers were abandoned in solid state amps. Ever since, well designed amplifiers used within their specifications have exceeded human hearing acuity.

Agree. That's why I use 37-year-old amp and receiver. I've participated in blind tests. They caused me to ignore all subjective opinions. That's why I always say "If you didn't hear it blind, you didn't hear it."

My 37-year-old amp and receiver have been serviced. Fairly inexpensive process. Hopefully will last another 30. And they're far prettier than today's amps/receivers. That said, I recently switched to a newer Class D amp because it has ARC, but I will occasionally use the old ones.

Oh, and while I'm making the case, double-blind listening tests are NOT scientific for the simple and very true reason that it takes at least days and more likely weeks or even months to get a handle on how an amp or other electronic component sounds

I have at least two problems with this idea.
1. A test that's good enough and scientific enough for every other field, including those involving life and death, is not good enough for audio?
2. If it really does take that long, then the differences would have to be so ridiculously minuscule as to be nonexistent or irrelevant.