Rigorous double blind a/b/c/d tests using real listeners has been performed, and the research has been published in peer reviewed journals since the 80's.
What has happened is that most of the audiophile community saw research as a threat to their revenue streams and actively FUD around it. And the audio engineering community has simply moved on.
Here is a talk that could be very informative. https://www.youtube.com/watch?v=zrpUDuUtxPM
His book is worth a read as well.
I said studies have been done that failed to show any difference, that's absolutely true.
I said I was open to hearing about recent papers published showing otherwise, yet you've provided zero links to a peer reviewed paper. You offer a Youtube video? If it's a video about research can we just skip to a direct link to the science? Citation please?
I said it's not necessary to know if current testing equipment can detect differences, to know if people can tell the difference. True.
Where are the rigorous double blind studies, with full disclosure, conducted with no conflicts of interest in funding or affiliation?
And of course I assume we want to stay on topic and look at research that isolate amplifiers for some tests, not conflate them with moving parts such as speakers.