Chris, thanks for pointing me in the direction of this thread.
I think of my music collection as a diary - specific albums are related to events in my youth and it's great to go back and play them, just as some folks like to get out their old photo albums.
I'm finding that some of my old rock stuff doesn't move me as it used to - and that's partly because my tastes are more sophisticated now. With my current system, I'm conscious of poor recordings and bad mastering - the lack of dynamics and where the bass has been cut to squeeze more music onto each side of the record. An example would be the bands Mott the Hoople and Sad Cafe which sounded great on an entry level stereo but sound flat and lifeless on my current rig. I think the reality is that we tend to think that the system we own is "good" and we enjoy our music at that level of reproduction, even though it may be colored and smeary. As we improve the quality of the components we own, the better records stand further ahead of the average.
I have also found that some records sound way better that I remembered them - the detail is revealed in songs that I now enjoy which I dismissed as boring "filler" tracks on earlier systems. Examples are Kate Bush's first album and Emerson, Lake and Palmer's first LP. The old cliche about hearing things you hadn't heard before in familiar recordings is true.
With classical music it depends on the recording/performance. I have a great version of the Rite of Spring (Barenboim on DG) which is thrilling to listen to but there are also a few classical records that are gray and lifeless that I can't play.
Finally, I now play music that I would have run a mile from. Travelling regularly to the US I made an effort to understand bluegrass (because I have friends who rave about it) and I now play and enjoy the Nitty Gritty Dirt Band - their records really come to life on a good system.