For example, in order to hear the difference between amps, wouldn’t you need better speakers first to hear the difference? So in my thinking, speakers advanced ahead of amps. It was only once speakers became good enough, that the more subtle differences could be heard. But is that correct?
Not to my thinking process, no. There is one implicit inferences which I disagree with:
A speaker that is resolving of amplifiers is going to be better at musical resolution
And I completely reject that notion today. I didn't used to. What I have found instead is that some speakers are more demanding than others. Often due to impedance dips and high phase angles in the mid to low bass. So at the extreme, what good does it do me to buy speakers which only sound great with megabuck amplifiers?
Further, OK, so this speaker can tell me the difference between a Parasound and Krell. Whoopee. Is that going to tell me anything about how it plays? Rarely is the answer here yes.
As I was discussing in another thread, the single piece of gear which makes you stop buying other gear tends to be good room acoustic treatments. They will outlive your gear, and you'll be happier with a wider variety of gear, and stop going the cable and tweak merry go round. Get yourself a great sounding room, and you'll settle into a great system rather quickly. Without this, you'll be churning amps and speakers forever.