I am afraid most android boxes doesn't support DTS pass through over hdmi (not sure about optical). If you can, try to install openelec in that box.
MINIX supports Pass through over HDMI and Optical. The difference is, HDMI carries Stereo output while the SPDIF carries the DTS/DD output. The decoding would be done by external device (AVR/DAC) in such cases.
AFAIK, HDMI is the highest possible bandwidth carrying connector in any system. So in general, if a system is designed to give DTS passthrough over SPDIF, it must provide the same over HDMI.
I am not really sure about MINIX though. I never used it.
This is for quick reference:
http://www.avsforum.com/forum/90-receivers-amps-processors/1315890-hdmi-vs-s-pdif-audio-faceoff.html
Other FMs please share your thoughts.
I use a MINIX Android player and I do following settgins:
1. In Android -> Sounds Settings -> Sound manager -> Set output to SPDIF Passthrough
2. In Kodi -> Audio, I set the audio as 5.1 and Passthrough device.
5.1 option is disabled for me.How to get it in Minix??