Originally Posted by Ted99
I have an Amazon Fire 4K for Amazon Prime streaming so that I can get Atmos and an Apple TV 4K so that I can get Netflix Atmos. Both are fed to my 4K TV thru the X4400. As we all know, the streaming Atmos sources are object-based dolby atmos carried within a dolby digital+ bitstream and not "full" Dolby Atmos. Both devices show "Atmos" as the input when an Atmos-encoded program is streaming and the output shows all the speakers active when I press "Info" on the X4400. But, when I am streaming a non-Atmos program, the X4400 "input" shows "multi-channel" input, not "dolby digital".
"Multichannel" input means that the player device (your AF4K or ATV4K) is providing a multichannel PCM signal. You'll only see "Dolby Digital" if the soundtrack's encoding coming into the receiver actually is Dolby Digital.
Edited to add: Apple TV 4K does not use Atmos over Dolby Digital Plus. Instead it sends Atmos audio to the receiver over PCM, using Dolby MAT v2.
The "output" shows all channels active.
That means that one of the upmixers has been selected.
When I use the green button on the X4400 to scroll thru the options, I get a lot of different ones, but not "dolby digital".
"Dolby Digital" appears only when the input signal is actually Dolby Digital. Since you're listening to a PCM signal, not to a Dolby Digital signal, the option to "play this Dolby Digital signal with no upmixing" is not available. You need to select the equivalent Sound Mode option "play this multichannel signal with no upmixing".
For a Blu-ray disc, the X4400 performs as expected. Is there a problem here?
Blur-ay discs use a variety of soundtrack encodings. When playing a Blu-ray disc, you'll see the option which corresponds to the actual encoding of the soundtrack that you're listening to. That might be Dolby Digital, DTS-HD Master Audio, or something else.