Wait, sorry, I guess this is the answer. So the technical stories and theories make them imagine they are hearing things? I really am curious about this process.
When you make a change to your system, if you think there is going to be a difference, you will hear it. Your brain hyper focuses on the music and now digs deep to hear note decays, silent background, etc. All of a sudden a "veil" is removed. Detail becomes luscious and more "analog like." More lifelike.
Now being assured that the change made a sonic difference, you go back to the old setting assuming it is going to sound worse. And worse it will sound.
This has happened to me countless times. I too can swear there is an improvement and a big one. Then I realize that what I thought could not have been there as often, I realize I had not made any changes!
Play a piece of music once. Then go back and play it again without changing anything. But now
focus on it to hear more detail. And more detail you will hear. You will hear it even though I just explained, and you know there can't be a change. Yet there will be.
The common retort is that people hear these differences when they are enjoying gear, not testing it. Problem is, they make the initial assessment when comparing gear, not enjoying music in a laid back position.
With the effect not being real, it will wear off. Then comes the next tweak/"upgrade" that triggers the cycle over again. Take notice that the people who "hear" such impossible things, have tried and swear by many impossible tweaks. The ethernet cable. The power cable. The stand. The footers. The tweaks to the OS. The special media player. Heck, even what SATA cable is in the computer!
They are living an illusion and simulation and not able to step out of it to see the reality. They could if they just listened to us once. Just once perform the same test blind. Alas, just like the movie matrix, they don't want to know. Knowing means eating crow. And eating crow is not what folks rather do with online reputation.