I had a long and bitter debate with Ethan Winer about this. My position is that there may be things heard which cannot be measured because the brain and perception are way WAY beyond our understanding at this point in our scientific understanding. His reply to that was, essentially, "No, it’s just placebo effect and subjective bias." (In other words, y’all are just in denial.)
I recall there was a really enjoyable exchange between Jay Luong of Audio Bacon and Ethan Winer in the comments on one of his reviews; probably the power cable one.
Summary off the top of my head is: Ethan said what you stated above, Jay imagined all of it, no proof etc. and also Jay had no scientific background. Jay responded he was an electrical engineer, Ethan said he must not be a very good one if he believed there were differences in power cables, Jay said he received a Bill Gates scholarship, so yeah he probably was a pretty good electrical engineer. Ethan did not have much to say after that. Quite comical.