Kodi 17 aac surround support to pcm or reencode?

Ive been running kodi 17 on my steamOS box. I have it set in pulseaudio to stereo output so that I can get normal dd/dts passthru working. I recently got some aac 5.1/7.1 files. When I play these I end up with stereo PCM. So just wondering what I might be missing settings wise to get surround PCM output. I no longer see a transcode option with kodi17 either so it doesnt seem like thats a possibility