LG CX, Sonos Arc, Dolby Atmos Audio Differences based on Format


Novice Member

Hopefully I am posting on the right thread but I have a technical related question. I have a LG CX, a Sonos Arc and an Xbox Series X. I have set up the TV with E-arc, Passthrough, Bitstream. The Sonos Arc is connected to the TV HDMI port 2 (E-arc). The Sonos Arc has been set up completely including True Play. My Xbox Series X is connected to HDMI port 1 (2.1) and the audio setting of Passthrough on the Xbox is selected. I also purchased a Dolby Atmos license on the Xbox so the Dolby Atmos Home Theatre is selected.

Now to get to the thing I am noticing. When I use my Web OS apps such as Netflix, Disney Plus, Prime I am able to get Dolby Atmos (DD+) but the audio seems to be much lower than if I’m playing PCM content. When using the TV built in apps I need to have the Sonos Arc volume set to at least 50% to be able to clearly hear dialog etc but it gets much louder during an action scene. now if I use Netflix on the TV app it is still Dolby Atmos (DD+) at a lower audio but if I go to Netflix on my Xbox Series X and play the same show (The Witcher) it now shows that it’s sending out Dolby Atmos with no (DD+) but the sound is significantly louder and seems to be better. Does anyone know why this is? Is it because the format on the TV apps are not utilizing all of the speakers in the Sonos Arc? Or is it that the Dolby Atmos is so compressed that I’m losing a ton of clarity. It feels like I’m not getting the best audio I can through streaming, any suggestions?


Distinguished Member
The Xbox over eARC is using Dolby MAT which is PCM + Atmos, so it can take the DD+ audio and pass it as PCM instead, its the exact same audio track.

As to the difference in volume levels I cant explain why, at a guess its down to how the sound system is designed to process the audio or requires adjust in its settings for processing it, does the Sonos have any kind of auto volume setting ?

There is a possibility Xbox might be doing some kind of auto volume, it does have a real time audio mixer.


Novice Member
Thanks for the reply,

It seems like all PCM content is significantly louder than Dolby Atmos (DD+) and I contacted Sonos and they ran a diagnostic and checked my Sonos Arc settings and said everything was normal they said it’s a formatting thing. Maybe in an update in the future Dolby Atmos (DD+) will be louder.


Novice Member
Did you find a good solution when switching between XBOX and other apps not running on XBOX? Or do you manually increase and decrease volume every time?


Novice Member
I thought the volume difference was because Dolby MAT is Dolby TrueHD and DD+Atmos over bitstream was just regular Dolby Digital...

Dolby MAT is also Dolby Atmos 2.0 because of the TrueHD and should sound better because HD audio just sounds better, although with the LG there is sync issues

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