Thank you, @trackbeo & @Millemissen for your input!
I think it will come down to a NAS solution.
When I’m not listening to music via my “normal” hi-fi system (I’m not getting
rid of my LPs, CDs, SACDs and BluRay audio), I use my PC (with external DAC
and monitor speakers), to which external hard disks (30TB) are attached, the
“extended” music collection, which is organized by its folder structure and
precise file names. I don’t use tags or playlists. And I would like to have
this interface or look and feel when I listen to my music via the A9 …
B.