Currently there is only an option to enable AC3 transcoding..
I have a DTS capable receiver
and I would like to be able to transcode AAC 5.1 to DTS 5.1 Audio..
I find that the audio is much better quality and louder on DTS than AC3.
and it also means I don’t need to increase my audio volume each time I watch any movies with AAC 5.1 that is transcode to AC3 5.1.
then need to change it/lower it again when I change to a 2 channel audio movie etc..
Please add this feature to a future update of Kodi.