Help playing 5.1 FLAC files

I have a bunch of 5.1 FLAC files I want to play on my Shield. I have HDMI passthru turned on and I’m sending the signal to my Yamaha RX-A3060 and then out to my TV. I can’t seem to get KODI to play the file as in 5.1.
Is there something I’m missing? I’ll try another program if it’s a KODI issue but I’m not sure on how to continue with this issue.