tl;dr: Turn on an equalizer and listen to a song you know well, then turn off the equalizer and listen again, then answer the poll. Extra credit: If you don't notice a difference in the unequalized song, try two songs in a row to see if the effect for you might just take longer to manifest. I saw another thread on listener fatigue posted here, but it seems to be more specific than what I was hoping to discuss. I’ve been playing around with equalizing to try to flatten out a headphone’s frequency response over the years and have noticed a few things during the process. In particular, I noticed that after listening to a song at moderate to low volume with the equalizer turned on, listening to it again after turning it off sounded worse than if I had listened to the song first without equalization. My conclusion is that within minutes of listening to music, my brain has at some level calibrated itself to the sound signature of a headphone. If this same effect is experienced by everyone, it would seem to me that most of the methodology used to compare headphones is flawed, but I might be alone in experiencing this, so I figured I’d start off with a poll.