@roxy54 Sorry, I'm certainly not intending to be obtuse but it's an important point I am trying to make. I am not trying to quantify anything.
If you refer to my contributions to the current string about the poll on sound perception of changes in power cords, it may become clearer. In that debate the question is whether people hear such changes. I am pointing out that any change in the sound caused by changes of power cords will emerge from the speakers. But what we receive from our hearing is not the same as what emerges from the speakers. It is that, plus the changes made by our conscious and sub-conscious brain input. Such changes are caused by all sorts of factors, but mainly centering around mood, in its widest connotation. In the same way we do not experience exactly the same taste from the same food and wine every time we consume it. Sometimes it tastes better than usual and sometimes duller. You might suggest that bottles of wine that are adjacent in the case can vary (not by simple being faulty) and indeed they can (especially pinot noir), but the changes we perceive go a long way beyond that. Sometimes a scene in a film or play (or a piece of music for that matter) may make us cry. But another time it won't. But what was on the screen or the speakers is just the same.