Using an Apple TV 4K, through SamsungTV audio on pass through, I am never fully confident that I am getting atmos.
On the app it show atmos and I can change the audio mode and it changes. When I go into audio settings, hdmi, and change the mode it doesn’t change the sound, but when I go into PCM stereo and change the listening mode, the audio mode does change, atmos music, sphere etc.
ATV passes an atmos container when the source has it (movies music). If no atmos is detected it falls to pcm 44 or 48 depending on the source (it up samples up to 48).
if you engage the “continuity audio” option, it switches to an “all atmos” container to make audio transitions easier between app/menus but it doesn’t necessarily means all the audio is atmos… it may be just pcm. I disengaged continuity to make sure I know what I getting upfront.
And on the tv side, make sure you have pass through/ bit engaged to ensure the tv sends what it needs to be fed into the hekla.