(...) And yet, the modern gear sounds just as different from one another as gear did in the past, despite the supposed advances you state. What would be then your explanation for hearing these differences? Our imagination? If real and not distortion, then what?
Yes, they sound even more different than gear from the past! As I said before we do not know the theory behind the reasons for these differences, no current studies were carried on these low level artifacts affect sound in stereo systems. In the high-end we rely on our subjective perception of the effect of these differences.