Weird one this, I have a generic android box which I use mainly for streaming from my pc. I generally use Kodi as a media player but only for local sources not online streaming or anything.
In the past when a file was in 5.1 I would have to set kodi to passthrough and it would show up on my receiver correctly.
Now one of two things happen - either it plays only in stereo, or a horrendous loud crackling noise plays.
I get the same problem with plex and the onboard media player so I've narrowed it down to not being a kodi issue.
I've gone through all the settings and just cannot get 5.1 to come through the receiver. If I put the PS4 on it instantly switches to 5.1 so I know it works.
So I'm figuring it is one of these problems:
1. The android box is just not playing 5.1 for some reason.
2. The HDMI cable is faulty (can this even happen, where it works but only in stereo).
3. The receiver has some setting on it for that particular input that stops 5.1 (I've gone through all of them and can't find anything to change).
I have an oldish pioneer receiver, a T9 android box and a samsung plasma TV.