Amplification: what are the biggest advances of the last 40 years?


As an audiophile most of my adult life but without any engineering expertise, I wonder how amplification has advanced since I started in this hobby as a high school student in the eighties?

Specifically, what has advanced the state of the art and what, specifically, make newer products sound "better" than older ones?

Is it that circuit design has advanced so much?  Or is the bigger difference parts quality and the technology leading to these better parts?

And please, none of the banal "it all matters" comments.  What I'm asking: which of the above matters the most?


bobbydd
Also a lot of the better solid state amps are designed with no inverse feedback that makes a big difference as well that's why I love Sim audio so much very analog sounding amp.
It would be helpful if people could list examples of the amplifiers with the features they think are such good improvements
Competition is the reason for the SQ we are getting today from amps. Also the number of world class speakers available at almost all price points can reveal a great amp from a good amp.
One reason I'm asking:

During a recent visit at my local dealer, I inquired as to why the new amplifier we were listening to was so expensive?

The reply was something to the effect that "well, the technology and parts quality of these newer generation " units are far beyond what was possible a few decades ago.  Also, that circuit design has advanced tremendously as a function of technology.

So I'm wondering how much any of these explanations are valid?
I am pleased with all my incarnations of my Bryston amps up top the present 7b3 (I have tried other makes btw). It is much a question of what you like ..
When I put in, now and then, my now ancient Threshold s1000's I still go "Wow - I love these"
What is better?
All depends as usual