No audio transcoding possible?

Is it possible to config the profile to not transcode at all if the container has both an audio and a video stream that is compatible with the client?
More specifically, I love the fact that Serviio is not transcoding my carefully encoded AVC streams in my MKV containers. However I'd love it if it just muxed my pure AC3 streams as well since my Bravia supports them. If it did this it would just be a a pure transmux operation and my NAS could even do that... More importantly I am hoping a mux would lessen my small AV sync isues I have.
Possible?
Cheers,
Zek
More specifically, I love the fact that Serviio is not transcoding my carefully encoded AVC streams in my MKV containers. However I'd love it if it just muxed my pure AC3 streams as well since my Bravia supports them. If it did this it would just be a a pure transmux operation and my NAS could even do that... More importantly I am hoping a mux would lessen my small AV sync isues I have.
Possible?
Cheers,
Zek