Not sure what point you are making?

Another observation - There are people on this forum who think they can hear differences  and there are others who tell them they are mostly mistaken.

Extrapolating from this. Maybe the question we should be asking is "Do some people have better aural perception"? or "are some systems significantly more sensitive to changes than others"? or even does understanding electronics introduce an anti placebo effect where a  no difference hypothesis is unfairly favored?

Andy