Though not the same files I used here for people to vote on recently, I used some similar files with someone I knew. Big time subjectivist and very, very confident of his abilities. That is okay, I was like that too at one time(well maybe not as arrogantly confident, but pretty confident).
So I send him an original and recordings of multiple DACs. He makes his choices, then reverses them, while explaining why he was hearing it alright just got it wrong. Asks which file is the original so he can have a reference. Make some more choices. Asks to know one of the DACs for comparison. Eventually there are only 6 possible choices with all I have told him. He has made 3 of them, listens some more, with flowery prose and explanations of the delicate perceptions that are only now coming clear to him with extended repeat listening makes a definitive choice about which is which. Goes on much too long about how sure he is now, why he is sure, what he hears that makes him certain, and says he would place big time money betting he is right. Yet despite the certainty tells me someone with lesser gear and lesser listening experience might miss it altogether.
I reveal what is what, and despite 4 shots of 6 possibilities he has missed it every time. He works things around after this, never admitting he ....was.....simply.....wrong and manages a face saving story that though confused by the testing procedure there is no question, NO QUESTION, the things he heard were real. I recognize some of the rationalizing in myself in times past. He is just as confident as ever while whiffing it 4 times (which at random he should have gotten right once 67% of the time). To me the flailing about and self serving, self reinforcing actions are obvious and embarrassing to witness. This from someone willing to do the listening and show what they can hear.
I have to remind myself to be kind, understanding and put myself in their shoes (and I once inhabited them mostly). Still................................WOW it is a big time head game we play on ourselves. I understand the attraction to, the sense of mystery, and personal discovery, the camaraderie the feeling of an acolyte reaching deeper levels of understanding and personal perception. Heady and highly satisfying addictive mind games there. I understand why it has an attraction and one is loathe to ditch it. Which is also why I think so many "trust your ears" audiophiles are not at all likely to put up and listen unsighted. It is so uncomfortable to risk that sense of special self one has built up. Yet it is simply them and they can't be otherwise than to go on at great lengths about all they hear when they know the gear in use. No wonder a common response if they do try it blind is that something is wrong with the test. The experience is so different (no bias from sight is not why it is different). It has such a different feeling it must be wrong it isn't how they normally listen. It should be obvious the different lost at sea feeling listening unsighted is a lack of their built up manufactured feeling for what they are hearing with familiar gear. Yet they can't accept that is so. You must be testing for the wrong thing if their finely honed perception suddenly vanishes.