Following this as well, I have the 6 series TCL.  I have it set to pass through, assuming that would be the best choice for the ARC.   I have yet to see the Atmos logo on the TV, but the Sonos app has confirmed it plays in ATMOS  when the source is in that format. 

Following, have the Arc & the 65" 8 series on order.

There's been talk that a firmware update will bring eARC to the 8 series, but another rumor says only the 75".

Hi, i have the tcl 75 615R playing the netflix, prime and disney doesn’t give me any atmos on the TV or in the sonos arc app., are you streaming it through the tv or through apple tv 4k?

I believe the 615R only supports Dolby digital plus, so if you wanted Atmos you would need to go from the Atmos source directly into the ARC.  Using the apps on the TV directly will only give you DD plus  
 

The Apple TV does support Atmos, but doesn’t have an HDMI ARC output, so you are going to need to get another source that has that, and supports Atmos.  I’ve heard great things about the Nvidia shield, but I’m not sure if that has an HDMI ARC.  

Streaming directly through the TV via the Roku platform

Wow Lucky you ! I don’t get any atmos at all in the roku platform except from the dolby channel. What exactly is the year, model and size of your R6 , What firmware are you on?

55 -R625. Purchased Dec2019.  Best $550 I spent ever lol

Firmware 9.3.0  Build: 4182  

Great, good to know that the r625 can do Atmos without a sweat , unfortunately in my region they still pushing the r615 as 2019/20 models and believe me it's driving us r615 owners nuts ! Anyway thanks for the reply and enjoy that panel in good health

Ed7 - I have the TCL Series 8 65Q825, Software 9.3.0, Build 4182-88, Roku platform. Dolby Atmos active streaming Vudu, Netflix, Amazon video, and Disney + via Roku.

Wow I'm jealous I guess owners of the r617 and r615 are still on the quest to get our Atmos working if it would ever work ! Anyway enjoy your panel in good health

Hey there! solved my atmos issues with Tcl r615 by an additional Nvidia shield connected via hdmi, now i get atmos on Netflix and Prime. Disney+ on the other hand still has no atmos but i guess it’s a disney issue not the TV nor Nvidia. 

I own a TCL 8 Series 65Q825. After setting audio to (auto passthrough) in the Roku settings the following apps all work with Dolby atmos sound on my Sonos ARC.

Netflix, VUDU, Disney + , Dolby, and Prime. Running Roku 9.3.0 build 4182-88

(just incase you all were wondering if this model works or not)

Finally I get Atmos on Disney+ on Nvidia shield , I just turned on the tv clicked on a starwars movie and bam! Sonos app confirms it's on Dolby Atmos DD+, no settings no tweaks it just worked . The Nvidia shield is fast , has games and upscales like a dream, additional expense but all worth it! Thanks and Godspeed everyone !  

Now that the new 9.4 firmware is out - can anyone confirm that the eARC works and that the Sonos Arc works well with the TCL 8 Series 65”? 658Q25

Confirm eARC works and Sonos Arc works well with TCL 75Q825 to include Atmos playback. TV audio setting is set to auto detect.