As the TV does not have eARC I suspect you may struggle to get it to play Atmos audio, even though the lossy codec DD+ is technically able to play on/through the TV Arc port - I have a similar situation with an older LG TV but had to resort to using an audio extractor, albeit I opted to use the Feintech VAX04101A, rather than the HDFury Arcana. 

However, just ensure you have set the Apple TV to not use multichannel LPCM and switch it’s sound-out to use DD+ (Atmos) and see if it might ‘pass-through’ the TV - I suspect it won’t work, but worth a try and if it doesn’t, then the Arcana or the VAX04101A is likely going to be the way forward, or maybe just live with DD+5.1 audio instead.

Around that time Samsung decided to drop support for DTS pass through, which also blocks Atmos-over-ARC. I can’t find your TV on rtings.com to determine if yur TV can pass DTS or not, but it is the most likely reason.

HD Fury or a newer TV with eARC are the solutions for this.

Based on my research, the Samsung NU8000 can only play Dolby Atmos audio from the native Amazon Prime Video app and possibly the VUDU app. Unfortunately there are only a few Dolby Atmos options on Prime Video. Try testing the Jack Ryan series, The Tomorrow War, Suspiria, and Carnival Row. You may need to change the audio after you begin playing the program to get it to play Dolby Atmos.

In order to get Dolby Atmos audio from the Apple TV 4K, you MUST have a TV equipped with HDMI eARC because the Apple TV uses Dolby MAT to play Dolby Atmos, not Dolby Digital Plus.

I found a user with your TV who was able to get Atmos from Netflix using an Nvidia Shield:

https://www.reddit.com/r/sonos/comments/hd1j2y/nvidia_shield_on_samsung_nu8000_2018_with_sonos/

Thanks so much guys, this was very helpful and I think I understand the parameters I'm working with now. 

@Ken_Griffiths - have tried what you suggested with Apple tv 4k previously and tried it again just to make sure, but when I turn of the multichannel LPCM (via "Change Format" to "OFF"), my only options are then stereo or Dolby Digital 5.1, there is no DD+ Atmos option. 

@GuitarSuperstar - your research was spot on, via the native apps on my Samsung NU8000 I was able to get Atmos via Amazon Prime but not HBO Max or Netlfix - and all your suggested titles played in Atmos.  It was nice to finally see the Atmos logo in the sonos app tho! 

Am now trying to decide whether to get an HDFury Arcana or an Nvidia Shield, as I've also come across several users saying their Shield is able to pass DD+Atmos to Sonos Arc through a non eArc TV. It looks like there are additional benefits going the Arcana route, such as lossless Atmos TrueHD. However, if I only stream my video, am I correct that I would never get that lossless Atmos anyway since all the streaming apps only utilize DD+Atmos? 

If so, not seeing what benefit there would be to Arcana for me, and the Shield is a cheaper and easier to obtain option (Arcana to me in Cali only ships from Taiwan). I really do enjoy my Apple 4k TV however, so I should be able to plug the Shield into my NU8000 in addition to my Apple tv and just selectively use Shield for Atmos programs via Netflix and HBOMax, right? 

All streaming apps use lossy Dolby Digital Plus to stream Dolby Atmos audio. Lossless Dolby Atmos/Dolby TrueHD audio is primarily used on Blu-ray discs.

For your setup, the main benefit to getting the Arcana is to use the Apple TV 4K. The Apple TV 4K is considered to be one of the best streaming devices available because Dolby Atmos audio is supported on ALL of the major streaming apps on the Apple TV including Netflix, Prime Video, Disney+, HBO Max, Apple TV+, VUDU, Apple Music, and TIDAL. I have an older TV with HDMI ARC and use the Arcana with my Apple TV 4K and it works great. And don’t worry about the Arcana shipping from Taiwan. HDFury is located in Taiwan, so they ship from Taiwan to their customers all over the world. And the delivery time is quicker than you would think.

So if I were you, I would go with the Arcana so you can play all of your apps (and get Dolby Atmos audio) from a single device that you “really do enjoy”.

Awesome, I think I will go with the Arcana. Thanks for the additional insight!