links at the end of the article which lead to scientific research findings.
Oh the "Resorces"-I thought those were kind of general reading links though on closer observation I see some are research papers. My comment is more that to a general reader the article is interesting but doesn't direct offer evidence of those assertions...which maybe doesn't matter a lot. I am curious now what studies show is the readily perceptible volume change, and now much it varies between individuals. Oh god I remember doing a test of a regular car head unit amp versus one with a Tripath chip. A bunch of managers and executives had come from Japan for some meeting and we're all listening to this A/B comparison with AT LEAST a 6 dB level difference between the two
If you tell a newbie that you can only reliably hear differences with controlled tests it is not the full truth, since you can distinguish bigger difference like a deeper bass or a stronger resonance easily and reliably without a controlled listening test.
I believe humans can easily imagine such differences, or perceive them due to listening more intently, etc ad nauseam. Which is why on the one hand I agree what you are saying is totally correct,* but I use the phrase "cannot prove."
*Loudness on/off or changing speakers or turning on Church/Hall/Jazz DSP and so on-really gross differences will definitely be perceptible without needing controlled conditions. But nobody argues about those, they argue about whether cables or DACs or power conditioning or pucks and so on make a difference. Items which from an engineering and physics point of view simply are incapable of making much change to the sound. So any change heard really has to be heard under controlled blind conditions or you cannot assert that a
physical change happened. (I also believe that
perceptual changes could absolutely happen validly in the brain even if no physical change occurred).