i've found something similar to what andy said for myself. my sq tastes haven't changed, so much as they've evolved. my journey started as a young dude back in the 80's listening to classic vinyl on my dad's home system through altec lansing stonehenge speakers. i always thought it sounded great but my ears were always wanting a little brighter sound. then in my teens i got my first home stereo consisting of mtx 4way tower speakers. even then i wanted to turn the highs up though it had horns. then in high school i got into car audio. i, again, loaded the car up with drivers and at one point had at least 3 sets of tweeters in one car! so time went by, more installs came and went. i also became a musician and learned to play guitar and drums. in this time playing insanely loud music, loud intruments and going to many loud shows, im sure my hearing got damaged. with my current system i find myself dialing the highs down a little bit, but probably not as much as i know they should be. at this point, with my experience listening and reading and more listening, i know i should have less but i think im just compensating for potential hearing loss.

this is just my personal story, but im sure others have their own. but like andy said, in the last few years i've had more of an understanding of what things should sound like and i think the best way to find that audible least common denominator is to just be patient. listen, listen, listen to as many cars and systems as possible. expand your understanding of what sq could mean to you because for me it has definitely evolved.

hope that helps