With your setup, you should be able to get Dolby Atmos audio from Atmos content on the Apple TV 4K. You do not need a receiver. You just need to have your TV and Apple TV set to the correct settings.

Great! thanks a lot… any chance of you knowing the correct settings?

I don’t own an X900H so I am not familiar with all of the TV’s settings. But I can tell you to make sure your TV has the latest firmware, be sure Bravia Sync (CEC) is enabled, speakers set to Audio System, and set eARC mode to on or auto. I believe there is also an audio setting that needs to be set to Auto 2 or Auto 3, but I’m not sure about this. Also, look for a Dolby Atmos or Dolby Digital Plus setting. If you want to send screenshots of the other settings, I would be happy to look at them.

Here is how to set your Apple TV 4K for Dolby Atmos audio: https://support.apple.com/en-us/HT204069

Thanks again!