Or wait for official firmware. We don't have a Yamaha amp but I'm fairly confident this problem will be fixed.
SUCCESS !!

New firmware fixes the bitstream audio problems; completely.
DTS-HD MA & TrueHD 7.1 all playing perfectly now on my Yamaha.
Checked all the Kodi samples and my own Blu-ray rips with various HD audio formats.
Now passes 88.2Khz, 96Khz and even 192Khz FLAC with no problems

Beck's Sea Change Pure Audio 192Khz is magic.....
Now I am a happy user and can start playing around with other features including Kodi.