7.1 passthrough including DTS:X and ATMOS will work with any version of Kodi when wrapper is installed (so playback is launched from Kodi but uses HiMedia video player). The settings to control passthrough when using wrapper are the system settings. So Settings - Playback from home menu.
Because Kodi changed how passthrough works, passthrough from Kodi internal player is broken until an update to fix it. You can get 5.1 passthrough back by installing the 'shitty' build (stupid name - all it does is restore audio passthrough from Kodi 16.1). See here: http://mirrors.kodi.tv/test-builds/android/arm/ and here: http://mirrors.kodi.tv/test-builds/android/arm/kodi-20170411-a4896c0-shitty-armeabi-v7a.apk