Hi @Raz7 

Welcome to the Sonos Community!

Off the top of my head, I can think of five different places where settings could affect which audio codec the Arc receives:

1. The Plex server’s audio transcoding settings
2. The Plex app’s audio output settings
3. The audio output settings of the device running the Plex app (if not the TV)
4. The TV’s audio output settings (and passthrough capabilities, though if the TV hasn’t changed, this won’t change)
5. TrueHD needs eARC to be enabled in the TV settings

All I can suggest is that you go through each of these and check what’s set. If the app shows “Dolby Digital + 2.0” then that is what is coming down the HDMI link - we do no conversions.

For what it’s worth, I have experienced similar issues (Dolby 2.0) with my nVidia Shield Android TV box and the Emby service/app (similar to Plex). The issue turned out to be that both Emby and the Shield were attempting to convert unsupported formats (I have an Amp which doesn’t support Atmos/TrueHD) into Dolby Digital. Disabling the conversion on one solved the issue, though I do get the occasional movie where I have to swap what performs the conversion to get audio.

I have Plex too, and have found it more difficult to get the desired results on it than on Emby, but I haven’t tried very hard as I prefer the Emby interface and free-tier features.

I hope this helps.

Thank you! Somehow this issue is just with the old movies when I am using the Fire Stick. Using my xbox is working fine as 5.1.

Hi @Raz7 

None of your devices care in the slightest how old a movie is - there will be a difference in the movie soundtracks that are working versus those that are not. Presumably, in the codec used. Be aware that many movies come with multiple soundtracks - please be sure of which one is in use, and try to avoid particular codecs if they result in stereo playback.

There is a Plex app for the XBox - have you tried that? You might get better results.

I hope this helps.

I believe it was the codec on that specific movie while playing it on Plex on Fire Stick. I normally select the best soundtrack available on a movie.

When using Plex on Xbox I have no issues with any movies.

Hi @Raz7 

In that case, I suggest that the TV, Plex server and Sonos are all setup correctly, and for some reason the FireStick is struggling with one particular audio format - just use the XBox all the time, or just when you encounter an issue on the FireStick.