Probably -
Audio device: HDMI
Number of channels: 7.1 (so your AVR can do the processing of LPCM according to your speaker setup) or 5.1 if you’re happy for kodi to downmix 7.1 material
Output configuration: Best match
Passthrough: enabled
DTS/AC3 passthrough: enabled
DTS-HD passthrough: enabled
TrueHD passthrough: enabled
E-AC3 passthrough: enabled
And keep in mind to disable “sync playback to display” under settings/player/videos for passthrough to work.
If you want your TV’s refresh rate to be adjusting according to the source’s frame rate, also set "Adjust display refresh rate” to Always or to On start/stop under settings/player/videos.