Don't think that solves the issue that in the example above I want to see the .ac3 file of one track and at the same time the .dts file of another.
This is what I have so far, but it needs a lot more refinement. Is the sort/sequence/sort/nodup all required, or is there a slicker way to make this work? Once I get the basic concept down I can start worrying about final sort orders and duplicate removal logic. FYI: 'Name (Base)' is a custom field with the base name of the track without any extra stuff like '(Live)' or '(5.1)' on the end.
[Channels]=>2 (tracks with more than 2 channels)
~d=a (include all files to see inside of stacks)
~sort=[Name (Base)]-d,[Bitrate]-d (first sort by bitrate)
~seq ~sort=[Sequence] (next add a sequence and sort by that)
~nodup=[Name /(Base/)] (finally remove duplicates)