I don't know if Ralph is right, but he has a lot of experience and makes highly revealing audio gear. Let's suppose that he is ...
Then, Ron, think how much difference what is in that 10% makes to our experience. Is it fair to say that within a fraction of contributing factors to our experience that all gear generally tends to sound similar, or each gear tends to be more different than the other. Or somewhere in between. I'm among those that believe some gear is definitely better than others - that's not an absolute, that's the way I hear - for me it is a fact. And even if you hear different than me (though I believe we hear more similarly to each other than not) within your preferences, I'll speculate that you find some gear is definitely better than others.
Perhaps our hearing system is such a finely discriminatory instrument that the 10% turns out - at least for us - to contain a significant range of variance. A range of variance large enough to challenge us, a range of variance we marvel at. A range of variance that shows the breadth of the hobby is justified. Do not despair.
It's more about the minimization of corruption of what came before with that 10%. Electronics and speakers, unfortunately, add a layer of synthetic to differing degrees and we are sensitive to these distortions because they are not from nature. Our evolutionary hearing system can tell if something is not from nature rather easily it seems and the best hifi is about removing things that our ear/brain considers to be 'synthetic'.