Ok so I need to make sure both my receiver and TV have the enhanced HDMI setting turned on then the game systems and also my Apple TV 4K I'm guessing will automatically detect the right settings?
It's the term for Sony TVs, but I just checked and it looks like Denon uses the same name.
On the TV you'd go to: Settings -> External Inputs -> HDMI Signal Format
There you can switch it from Standard to Enhanced for any of the HDMI ports.
It looks like Denon receivers have this too, so yes it looks like you'd change to enhanced hdmi on there too:
http://manuals.denon.com/AVRS730H/NA/EN/RQIFSYsvvlcemq.php
Yup, after turning that on, when you run the detection in the video options the device should be able to tell properly what your TV is capable of and therefore enable all of the options, then you may have to choose the best option from those settings.
For example, for the Pro that should enable you to be able to choose 2160p RGB from the list, which may have been grayed out before.
Edit: I saw you got another msg earlier from someone so you may have already done this. :)
