To update on my silly situation.
I went and got an AppleTV4K. I now get Atmos on Netflix and iTunes etc on Apple TV.
So far, I have had no problems. The issues I had with lip-sync that were present with my old Denon seem to have disappeared (both with match frame-rate on and off.) The HDMI-CEC works pretty much flawlessly, and the remotes work as intended, meaning 99% of the time I’m just using my tv remote or my Apple TV remote. The TV sound coming through the optical port also works brilliantly.
I am extremely happy with it. I would never consider myself an audiophile, although I appreciate good sound. I am quite sure I could spend double the money, and even more, and get something better (a true wired Atmos system.)
But it really sounds amazing.
I appreciate the clarity and variety of the sound. The soundstage is clear, when people are talking in different parts of the screen it really feels anchored to where the sound is coming from.
The rear speakers are great; there is often lots of colour and effect coming from them, without it feeling “obvious.”
The upward firing thing seems to work decently. Watching “Bird Box” on Netflix there were a few moments when sound clearly seemed to be coming from above, from gentle bird noises to loud thumps. I have no doubt all this could be tweaked further to be better and more accurate, and maybe I’ll play with it over time, but it is damn impressive for just unpacking it, plonking it in front of the telly and turning it on.
The other thing I appreciate is dialogue. It is clear, always clear, no matter how softly whispered, or how much dramatic music and sound is going on; but it doesn’t feel tiring on my ears (I’ve experienced that in some badly set up cinemas where you feel assaulted by the centre channel.)
Best of all is it’s low volume performance. I have never used a system before where you can turn the volume so low, and yet still have clarity on every word spoken. It really is brilliant.
I have no idea what people seem to complain about that the subwoofer doesn’t work - it is certainly working, in Atmos content of course, but also impressive in 5.1 content, and in normal TV sound coming over Optical, everything is nicely fleshed out by the woofer. Music too is really great to listen to (via Apple Music on aTV, haven’t tried Bluetooth), vivid and colourful, and fleshed outs with the rears.
Aside from my idiocy with the Apple TV and getting true Atmos working, the rest of it has been set-and-forget. I haven’t even dared try the “surround/smart/standard” buttons in case it ruins what is happening automatically!!
For £750 I think I have gotten a damn good piece of machinery at a very good price.