I am talking just for discriminating Audiobooks AND Music.
There is a quick-filter for folder; now I don't know if this looks for PART or ALL the path (@Tim Curtis can comment...), but if you put them all under /Audiobooks, while you music under /Music, maybe it's possible to filter by folder...
ETA
Just checkd, my music is grouped at artist level under the first letter; using quick-filter "folder /Music/B" gives me exactly that: everything under /Music/B, so in your case "folder /Audiobooks" and "folder /Music" should lead to the initial desired functionality.
There is a quick-filter for folder; now I don't know if this looks for PART or ALL the path (@Tim Curtis can comment...), but if you put them all under /Audiobooks, while you music under /Music, maybe it's possible to filter by folder...
ETA
Just checkd, my music is grouped at artist level under the first letter; using quick-filter "folder /Music/B" gives me exactly that: everything under /Music/B, so in your case "folder /Audiobooks" and "folder /Music" should lead to the initial desired functionality.
