> people who are really into it can really hear it.
Citation needed. Sometimes they can, but a large part of the time they are claiming things that they cannot hear if tested. They of course refuse scientific tests.
There is a big "emperor has no clothes" effect in high end audio equipment. It is hard to measure, there's a big cognitive effect where it sounds better because you know its expensive, but on the other hand, with the right setup it's trivially easy to demonstrate where higher quality equipment is perceptually better.
It's one of those things where the people who talk about it the most have the least idea of what's going on, but that doesn't mean there isn't anything going on.
Citation needed. Sometimes they can, but a large part of the time they are claiming things that they cannot hear if tested. They of course refuse scientific tests.