Rule #1 - Be Patient - Rule #2 - Don't ask when, if you don't contribute - Rule #3 - You have coding skills - LinuxMCE's small brother is available: http://www.agocontrol.com
Then select 'HDA NVidia NVIDIA HDMI (ALSA)' as output for all items in 'Sound Prefrences' and select 'HDA NVidia (Alsa mixer)' as the mixer.