[popcornmix]

How do the Netflix and Amazon addons choose the default audio stream ??

In my Kodi setup - for some reason - the audio settings have the number of channels set to 2.0. But the addons still default to the 6 channel DD setting and I hear no sound (or occasionally very weird effect where you hear the background music and very faint voice channel). If I change the stream to the DD 2 channel setting then I get sound. I have tried changing the audio setting (in Kodi) to 5.1 (and the Pi is connected via HDMI to a 5.1 amp) but still hear no sound when the addons used the 6 channel DD stream.

I have tried changing the audio stream, in Netflix, to the 2 channel DD and clicking on the make this the default setting but when I switch to Amazon the audio stream is back to the 6 channel option as (presumably) it doesn't have a 2 channel DD option (just a 2 channel AAC one).

Does that make sense to anyone ? Is it possible to set it up so that it never picks the 6 channel option ? Or is my setup wrong - and 6 channel sound sould be possible ?

 Your setup sounds wrong. Many video files only include a 6 channel audio track, and many users have only stereo speakers - with the correct settings kodi will decode the six channel audio and downmix it to stereo.
You don't need a dedicated stereo track.

I'd start by choosing "reset all options to default" in the setting/system/audio. That should be configured for stereo output. Does that work for you?

I suspect you either don't have number of channels set to "2.0" or you have passthrough enabled currently. And your 5.1 amp isn't configured properly to handle 5.1.