One other thought/memory occurred to me that I thought I'd mention. Don't know if this resonates with you at all, but just in case:
There are definitely some beloved recordings of mine that have a different overall feel to them now that my system is (as far as I know) has lower noise, less distortion, and (as far as I know) greater frequency linearity than it used to; and now that my room is larger and has (again as far as I know) better control of resonances and such. One example is
Led Zeppelin II. I mention this album because the recording is full of distortion - intentional distortion on the guitar, bass, drums (sometimes), and theremin; distortion on the mic preamp; distortion from the ancient tube equipment they were using to record and mix it; distortion from the tape bleed between tracks; and distortion from tape overload all over the place.
When played on the version of my system I had 5-7 years ago, in my previous, smaller room, I was less conscious of all this distortion. Of course I could hear it, and I could pick out the likely source of any particular moment of distortion if I wanted to. But the entire album sounded like a cohesive, organic whole, especially tracks with loud/intense parts like Whole Lotta Love, Heartbreaker, and Bring It On Home. And the music just filled the small room I was in, sometimes feeling bigger than the room (even though the actual L-R soundstage was not wider than the room and the soundstage depth was not great).
Now with my current setup and room, music has greater soundstage depth, width, and precision, and greater clarity. But this album/recording itself sounds nearly as distorted as it did before, because the distortion of the recording was by far the majority of the distortion I was hearing before. So now it's sort of like taking an old, worn but beloved photograph and putting it in brand new frame with clear glass. The old photo (the music) has become larger, but the frame (the room) is larger still. So the music is still wonderful - but there's a much clearer difference between the distortion of the recording and the clean, dead-silent backdrop of my system. And while the music is big and deep, it no longer feels like it can outgrow the room.
Now, for me, none of this is bad - in fact, it's more exciting to me because I can hear so much more.
But, I also have
other music, which is more modern and better recorded, which previously would never sound quite as big as Zeppelin, but which now does, albeit in a different way.
So I can see how some of one's favorite music might lose some of its exceptional, magical qualities that might have made it unique or a total sonic standout before.
I don't know if any of the above makes sense to you (or anyone else). But I thought I'd give it a try.