HDMI ARC can send Dolby Atmos with the Dolby Digital Plus audio codec. You need to make sure that both devices support HDMI ARC and that the TV is capable of sending Dolby Digital Plus, not just Dolby Digital through HDMI ARC. ... If both devices support HDMI eARC, then Dolby Atmos is definitely supported.

Can you get Atmos over ARC?

While Dolby Atmos can be passed over regular ARC today (via Dolby Digital Plus) eARC offers improved bandwidth for higher-quality Dolby TrueHD and DTS-HD Master Audio streams, including Dolby Atmos. The new format also has lip-sync compensation built-in.

Does Dolby Atmos work without eARC?

You do NOT need eARC for this. Regular ARC can send this fine from your Atmos source device (be that your Apple TV or internal TV apps if your TV supports it). Full Dolby Atmos - this is uncompressed Dolby Atmos.