There is without a doubt some mental burn in that takes place when people say "unlistenable out of the box" whether they like to admit it or not (whether this has to do with ego, buyers remorse, etc who knows). I experienced it a few days ago hearing Thiel speakers. Super bright when I first heard them, eventually adjusted to the sound...went back and played the tracks that I thought were super bright and they remained only "bright" and my brain had adjusted. Line level was digitally controlled so the volume was exactly the same.
There is a lot of psychoacoustics that some people flat out refuse to believe exists.