Two values of Albumtitle would be nice

[simoncn]

You could do the following:

1) Add DISCSUBTITLE tags to your files in addition to ALBUM tags, as suggested by stefano_mbp
2) Add a tag name AlbumTitle to the indexTags property
3) Add the following to the tagValue property: AlbumTitle.merge={Album, DiscSubtitle}

After restarting MinimServer, you will see a new index AlbumTitle containing a mixture of top-level album sets and individual album names.