Will new Sonos ARC provide full featured Dolby Atmos quality sound when connected to: 1) ARC-enabled Samsung TV (Q9; late 2018 edition); and 2) latest Atmos-enabled 4K Apple TV?

Hi - i have a Samsung Q90R , Sonos ARC and heres my experience with the setup:

Connection is: Arc>TV>Various Devices

Internal Apps: Atmos for Netflix, Amazon Prime. Not detected for Disney+ or Apple TV

Amazon Firestick 4K: Atmos for Amazon Prime, Disney+ (symbol but limited due to Europe restrictions. Not detected for Netflix

BT Youview:  No Atmos for internal apps

PS4 Pro: No Atmos passthrough for any internal apps

No lip sync issues encountered.

I took a look again just now on both Netflix and Amazon, both through the Samsung apps and via Apple TV. I can only see content available in up to 5.1. However, I can confirm that the HDMI ARC connection is at least passing this through in all cases. I could swear I was able to find DD+ yesterday but I just don’t see it now, even after having gone through a bunch recent uploads on the two services.

My understanding of HDMI ARC is that it’s just a two-way link and there is no difference in the cabling. Anyhow, I ordered a splitter and will try it out, but I’m guessing that we’ll need Sonos to update the Arc for LPCM first so that it can decode the Atmos signal that the Apple TV 4K actually sends. In the meantime, 5.1 seems to work fine.

In case it helps anyone I’m getting ATMOS through the netflix app on an LG b7 oled, not bad for a 2017 tv!, prime only seems to be did, switching out the hdmi cable with the supplied one did the trick, oh and it sounds absolutely incredible

I also have a Samsung 75” Q9FN, with Sky Q.

My ARC arrived this morning to replace my Playbar. I already have the Sub and Surrounds. 

I already knew the Q9 does not support eARC. The Sonos ARC is connected via HDMI/Arc

Neither the Samsung apps nor Sky Q will output ATMOS in my setup - only DD 5.1

It is disappointing the TV does not support eARC considering I paid a significant sum of money for it, but there ya go - my mistake. I didnt realise I was gonna want eARC further down the road.

I’ve a Samsung Q80R as well. I can get nothing but 5.1 out of the Arc and it says on the Sonos app system setting that the Arc input is stereo 2.0 from the UHD Blu Ray. I tried resetting the TV to factory settings and briefly it showed that I could access Dolby Digital plus in the settings rather than PCM. But as soon as I set up Netflix again I noticed no Atmos note on movies I knew had it, went back to settings and it had reset to PCM with the Dolby options greyed out again.

I bought the Arc knowing I didn’t have E-ARC HDMI on the telly but had read that Dolby Atmos was available through just HDMI ARC so I thought `you beaut! I’ll have that then’. 
But telly says nooooo.

@jam9 id be curious if the splitter works. Everything I’ve read would suggest not but… worth a shot a suppose! I’m curious. 

Mine arrived two days ago and I have a qe49q70r (2019).  It doesn’t appear that I'm get ATMOS through the built in Netflix app (I can’t see the ATMOS logo in the Sonos now playing screen.)

Where do you look to see if you’re getting DD or DD+?

thanks.

Just to follow up on this post, I’ve pre-ordered one of these: https://www.hdfury.com/product/4k-arcana-18gbps/. It’s currently in development but is supposed to allow you to split output from an HMDI source to your TV and to the Sonos Arc via eARC. I don’t like having to spend so much when I think Sonos simply could have done a better implementation of connectivity to the sound bar, but if this works, I’ll be happy. In the meantime, I am enjoying getting Dolby DD and the sound is generally very good.

I think you’ve gotten some good answers here and I’ll echo @jam9’s recommendation of the HD Fury Arcana (https://www.hdfury.com/product/4k-arcana-18gbps/) for the following reasons (based off your original post and some of your other comments): 

• While some people have gotten lucky getting Atmos from Apple TV over regular HDMI-ARC, because of the way that Apple sends Atmos (basically LPCM in a Dolby MAT container - don’t ask) whether it will work for you or not is highly dependent on your TV model’s audio capabilities. Arcana takes your TV and its audio capabilities / limits out of the mix and sends whatever the Apple TV is capable of directly to the Sonos Arc. 
   
• There’s a lot of discussion about “full” vs. “limited” Atmos, but Atmos is Atmos regardless of how it’s being transmitted. Yes Atmos can be sent over “lossy” Dolby Digital Plus or over “lossless” Dolby TrueHD, but, as another poster very correctly said, it’s highly doubtful you’d hear a meaningful difference on the Sonos Arc. 
   
• And, since you don’t use Blu-ray Discs and only watch via streaming apps, then you’d only ever be getting Atmos over lossy Dolby Digital Plus anyway, so it’s a moot point. 
   

So, in a nutshell, the HD Fury Arcana is, so far, the only sure bet that will give you the full sonic capabilities of your Apple TV when paired with the Sonos Arc (short of buying a new TV, and even then we’re still seeing plenty of issues with eARC-compatible TVs). I’ve got an Arcana on pre-order myself for my Apple TV 4K / Arc / Vizio E70-F3 setup and I’m looking forward to receiving it.