@holmz
But if we assume that some amps were possible with a vanishingly low THD+N, then they would sound the same regales of topology
There are indeed those who claim once a certain level of performance has been reached, then products would indeed be indistinguishable from one another. I believe there have been rather rigorous tests done which seem to bear this out.
As I said, Fletcher-Munson and other such empirical studies have predictive power in a general sense but are weak on an individual basis. Additionally, personal preferences when it comes to audio gear is not based solely on sound, in any case. There are several other factors buyers consider when making a purchase which factor into a decision. It’s a complex decision that one needs to ultimately make for one’s self in the proper context.
Sure, a person could choose a proxy and take a chance. It all depends on risk tolerance and finding a suitable proxy. Me, I prefer to judge for myself as finding someone else with my tastes, the same gear and acoustical space, would be more difficult, time consuming, and risky than just trying the equipment myself. Besides, even if I associated myself with a "like minded group", the critical issues of component interaction and acoustical interaction in my space would make it impossible to find a realistically "safe" bet.
I don't believe your analogy is appropriate, either for those "cable deniers" who base their argument primarily on an intellectual argument- it's a belief system, not a perception driven matter of taste, nor for those who simply claim that they hear no differences. That is more a pure perception argument rather than a matter of taste. In either case, it isn't a simple matter of taste at work, unlike the debates centered on amps, etc.