My experience is similar to a lot of people here. I see that we’ve all had our hurdles over the decades while moving OS’s and I’ve used many of the apps mentioned here (Windows/Linux). I couple of years ago i decide to stream my music because i was already into self-hosting and i really needed to properly tag my music for whatever server app I would use.
I always had my music structured by folder, i was using desktop apps for playback so it kinda worked for me. But i wanted to have better tagging. I had already used kid3 and picard but it lacked automation so I used beets for the albums on my collection (about 12K of songs). It wasn’t perfect but the software is not blame and it was a great way to tag automatically and move files for a consistent folder structure to match my needs.
Right now, since i don’t add music all the time ( a couple per week) i mainly stick to picard to tag new albums. it has 3 actions to manage the files on disk (move, rename, tag), I have script rules for naming files (if required) and i use the ReplayGain plugin. But I also have to point out that the learning curve of picard is rather high, the UI is a mess and it took me a really long time to understand how it works or where the options are.
After trying airsonic for a while i moved to Navidrome and have been using symfonium (android) and Feishin (desktop). It’s the best experience I’ve had since i started listening to music on my pc (199…6/7).
Regarding the source files, it lives on a disk and is backed up to another disk, managed on openmediavault.