If you want the best audio from the Apple TV 4K, you want all 5.1 audio to play as Multichannel PCM 5.1.

FYI… most of the major streaming services use Dolby Digital Plus audio, not Dolby Digital.

All streaming services use DD+ for Atmos, so you aren't getting anything but DD+ no matter what the label says.  The only sources for lossless Atmos are Blu-Ray disks.  And multichannel PCM is just the Apple TV pre-decoding the source into PCM.

Maybe this chart summary will assist you…

Generally speaking…

Apple TV uses the Dolby MAT container that holds Multichannel LPCM ‘uncompressed’ audio and if it’s Atmos content, it also contains the Atmos metadata (object data) - You will need eARC enabled for this uncompressed format,  so it’s best to leave eARC switched on and have the TV support audio pass-through on its ports. If you switch eARC off, then the audio sent to the TV/Receiver will drop back to PCM stereo instead.

Dolby Digital Plus Atmos is a ‘compressed’ format and it will work with HDMI-ARC (aswell as eARC) - this codec is used by most TV’s and their built in services, like Netflix, Prime Movies, Disney+ etc; but sometimes the App (or the TV) may not support Atmos audio and you may find the audio defaults to Dolby Digital Plus 5.1 or Dolby Digital 5.1.

The audio format/codec sent by a source device to a speaker, is dictated by the device in the chain that has the lowest common denominator in terms of audio capability - so it usually best to set any device to its highest possible audio capability - so I think you’re best to leave the Sony TV to these settings;

• eARC: Auto
• Digital Audio Out: Auto 1
• Dolby Digital Plus Output: Dolby Digital Plus
• Pass Through Mode: Auto

The above is what’s usually recommended for Sony TV’s.

Hope that info. assists …

So when I am not playing Atmos content, you think Multichannel 5.1 is better than Dolby Digital Plus 5.1? Meaning I should leave eARC and Passthrough set to “Auto”?

99% of my viewing is from my Apple TV4K…with that said is there a benefit to turning on eARC and Passthrouhh to Auto?

I always thought Dolby Digital Plus 5.1 was better than Multichannel PCM 5.1? So that’s why I was considering leaving eARC and Pass Through set to Off.

I do have a 4K UHD player, but I rarely watch it…I would obviously benefit from turning on the eARC and Pass Through to Auto, right?

Maybe this chart summary will assist you…

Generally speaking…

Apple TV uses the Dolby MAT container that holds Multichannel LPCM ‘uncompressed’ audio and if it’s Atmos content, it also contains the Atmos metadata (object data) - You will need eARC enabled for this uncompressed format,  so it’s best to leave eARC switched on and have the TV support audio pass-through on its ports. If you switch eARC off, then the audio sent to the TV will drop back to PCM stereo instead.

Dolby Digital Plus Atmos is a ‘compressed’ format and it will work with HDMI-ARC (aswell as eARC) - this codec is used by most TV’s and their built in services, like Netflix, Prime Movies, Disney+ etc; but sometimes the App (or the TV) may not support Atmos audio and you may find the audio defaults to Dolby Digital Plus 5.1 or Dolby Digital 5.1.

The audio format/codec sent by a source device to a speaker, is dictated by the device in the chain that has the lowest common denominator in terms of audio capability - so it usually best to set any device to its highest possible audio capability - so I think you’re best to leave the Sony TV to these settings;

• eARC: Auto
• Digital Audio Out: Auto 1
• Dolby Digital Plus Output: Dolby Digital Plus
• Pass Through Mode: Auto

The above is what’s usually recommended for Sony TV’s.

Hope that info. assists …

I am going to give this a shot. I understand that Atmos content is better with eARC and Pass Through set to Auto…my two questions are…

I just thought that Dolby Digital Plus 5.1 was better than Multichannel PCM?

I also thought Dolby Digital Plus 2.0 was better than Stereo PCM?

Are those incorrect assumptions?

Also - I notice Multichannel PCM 5.1 plays the sound a lot softer than Dolby Digital Plus 5.1. 
 

I really have to raise the volume on Multichannel PCM 5.1 compared to Dolby Digital Plus 5.1

@Corry P wrote this on another thread:

“Differing content can often be mastered to different volume levels, and when a change in encoding is involved, this is even more likely as the sound track will be adjusted to best fit the parameters and abilities of the codec. Technically, however, LPCM isn’t a codec (it’s uncompressed) and is in fact how all digital equipment handles sound internally - at some point, regardless of any formats/codecs/channels being used, everything is converted to LPCM before being passed to the digital amplifiers inside all Sonos speakers/Amps. Included in the decoding process of Dolby Digital and Atmos to LPCM is a volume boost/range compression. As LPCM isn’t processed (decompressed) like a codec, there isn’t the same opportunity for this to happen. When LPCM is played, you get the closest to the original track possible - the data on the source is relayed directly to the amplifier after mixing.

Therefore, varying volume levels are normal...”

I saw that response and I’ve done a bunch of research over the last week or so and it seems like many people are having issues with LPCM sounding very low on the Arc (compared to DD+) and the issue keeps being ignored as normal.  
 

The same people that had issues eventually got another soundbar and the LPCM didn’t sound low - this has to be something related to how the Arc handles it LPCM. 
 

With that being said, I do all my watching on an Apple TV 4K. I notice with eARC set to Auto it shows Atmos and with eARC set to Off it shows Atmos (DD+).
 

1. Is it true that all the Atmos content through the Apple TV 4K only plays in Atmos (DD+)? If true, I may just leave eARC off since I get Atmos (DD+) and for all non Atmos content I get DD+ (which sounds better than LPCM). 
 

2. Is it possible to get Atmos from the Apple TV 4K? Or only when streaming from a 4KUHD player?

Thanks again for your assistance. 

@bignicknicknick Don’t overcomplicate it. The recommended settings is keeping eARC and Pass Through Mode set to Auto on the TV. This will result in Dolby Atmos audio from all Atmos content and Multichannel PCM audio from all 5.1 content. But if you don’t like the way Multichannel PCM sounds, then use whatever settings that sounds the best to you. Just enjoy your system.

I do all my streaming from the Apple TV - so I’m not sure if I’m really missing out on not using eARC. 
 

Trust me, I want to use eARC…but Multichannel PCM sounds terrible compared to Dolby Digital 5.1. 

I just with @Corry P could provide an update or get someone on the engineering team to look into this.

The word “terrible” does not help in addressing your problem. Can you clarify?

Hi @bignicknicknick 

I don’t really have anything to tell you - I don’t recall hearing of this issue before. In addition, I don’t own an Apple TV and never will, so I can’t confirm it’s behaviour, but a quick Google search shows me that for some strange reason they do not provide an audio passthrough option like most devices - I can only suggest you contact Apple to get them to add the option (though it seems people have been requesting this for years), or use a different device like an nVidia Shield (I have one of these and think it is great). In my opinion, I suspect they have done things this way so that you are more likely to get audio of some kind or an other, in order to make their device “just work” with a minimal amount of settings being changed, which I guess in their eyes is better than getting no audio at all before any settings are changed.

In terms of LPCM being at a different volume as compared to Dolby Digital + (or other formats), this is expected and pretty normal.

I hope this helps.