[hdmkv]

With regard to multichannel AAC and (L)PCM support, is this being worked on by CE developers?

To answer my own question, found this from a CE developer:

The problem with audio formats like AAC and FLAC is that you can’t bitstream them. They have to be decoded by Kodi and then sent as multichannel PCM signal to the AVR.
At this stage multichannel PCM support is not implemented in the 4.9 kernel.
I believe that there is a dev at HK who is working on adding support for it, so hopefully it will be available sometime in the future.