Yes, I've done this but how can I make this sort order persistent?
Sort order should "stick" in each view. A view is Albums, Artists, Files, Genres, etc. The top level items under Audio in the tree on the left. Each view has it's own sort order. But once you set a sort order for each view, it should stay how you set it.
[About remembering deleted files]
No, it's enabled and the files are initially removed from the library when I delete with the "Remove From Media Library" option. However, at some later time when I return to an artist where I've "deleted" tracks, I sometimes find they have returned.
I'm just guessing here, but with such a large collection, I think you're just finding more duplicates. Just a guess. Nothing should "reset" this status without you doing something special. Oh! If you move files around on disk outside of MC it will try to re-import anything you move around that's still in an auto import directory. Maybe?
If I could create a search/filter that would only show me all non-FLAC tracks for each artist->album where FLAC tracks exist it would make this fairly simple but I can't figure out how to do that. The search logic is:
1. Find all FLAC tracks
2. Within these search results find all non-FLAC tracks for each artist-album.
Step 1 is simple but I can't figure out how to do a search within search results, is this even possible? Is there another way to do this?
My duplicate finder view could do this fairly automatically I think. If you select "Artist, Song, Album" it should only show exact duplicates based on those criteria. Then it will show them all to you, sorted how you choose. Then you can use the File Type pane to select FLAC, MP3, etc to isolate your selection further. I think that would work just fine for you. But it's semi-manual. You probably wouldn't trust any pure search that just showed you a list of MP3s would you? You wouldn't bulk delete 20,000 tracks that a search showed right? You'd want to review them and then delete when you were sure. The Duplicate Finder view *helps* you find and review and the deleting is up to you.
To further clarify, I really have 1 primary problem which is the two-step search I described above. If I could do this it would make it simple to locate and bulk delete the mp3, mp4 and acc files I no longer need because I have upgraded artist-album to hi-res FLAC.
Hmm. I'm not 100% sure how to do exactly what you're asking. I understand it, but right this second I'm not sure how to get MC to do this "pairing" and then remove one of the pairs based on file type. I can do all kinds of things that are similar. But not exactly that. I'll think it over.
I still think a semi-manual, assisted process is the way to go. That way you're really really sure about what you delete. Even with 30,000 tracks to review, that's about 3,000 albums. You could probably review one album every 5 seconds. So you could do something like 700 albums in an hour. Let's round down and say 500 albums in an hour. Assuming 10 tracks per album, that's about 3,000 albums, so maybe 6 hours total to de-duplicate 30,000 tracks (3,000 albums). Big collections require big effort to organize and maintain.
Brian.