My DVD player will play 4k blu-ray dics and my AVR decodes the Atmos no problem. I just had a problem with streaming Atmos and now I got it to work with the TV apps and my receiver through ARC. Sounds like you are all set. Other options are Xbox or Apple 4K TV. Check on Netflix for the list https://help.netflix.com/en/node/64066 4k Roku and Fire are Atmos for Prime but not Netflix. DD+ Atmos is a compressed version of Atmos so don’t expect Blu-ray quality. :)
