Is there any interest in obtaining a true 5.1 source or using the 6.1 source from the blu >rays etc?
- Rev
If you need to cure your 5.1 fix, on the 'spleen there are audio files for the Star Wars Original Trilogy (aka. GOUT) that uses the rarely heard 1997 Special Edition sound mix made from the original CinemaDTS CD-ROM discs. Of course, portions of the audio include the sound mix from the GOUT to patch over footages where the 1997 SE audio would be out-of-place.
Just mux these to the MKV video and you are good to go.