Changes made with no fix:
– Mint 18 x64, Mint 17 x64
– 2 different kernels
– different settings in Pulse Audio
– Kodi 16, Kodi 17 beta
– onboard sound, discrete sound card
Nothing I have tried will get DTS pass-through working and here is the kicker – it works just fine with VLC player. Same file played with VLC passes DTS just fine to my AV receiver. Just to be clear, I’m using the optical interface for audio from my HTPC. Any ideas or suggestions would be greatly appreciated. I really want to use Kodi for my movies but I also have to have DTS support. 
HTPC rig:
AMD Athlon II x4
4GB RAM
128GB SSD
Gigabyte GA-MA785GM-US2H mobo
MSI GTX770 4GB video
Realtek HD ALC889A onboard audio