How about an entry "Custom" in the Browse List, next to "Artist", "Album", "Genre", etc.
There one could create Sorting lists customizable with arbitrary tags.

E.g. one list displays <expression1> SORT BY <sort-pattern1>.
Selecting one item of that list optionally displays a sublist <expression2> SORT BY <sort-pattern2>.
The number of sublist hierarchy levels should be selectable and the last sublist displays the individual tracks.

The expressions could be anything according to
http://wiki.hydrogenaud.io/index.php...0:Query_syntax
http://wiki.hydrogenaud.io/index.php...ting_Reference