It is possible to insert 6.1 sound from the Blu Ray to the Despecialized edition, however the Blu Ray is the special edition cut with added shots not seen in the Despecialized edition. Therefore, the audio would have to be edited down to fit the Despecialized edition. Also, special edition audio that would be inappropriate for the Despecialized edition have to be removed and replaced with the Despecialized audio, like Luke’s scream as he falls down the Bespin reactor shaft in the SE cut (what I hear among the OT community, that is a pet peeve).