If I understand the answers in this thread correctly, my situation similar to the question posted by JohnB352 and I'm good to go. I can accept a lossy surround 7.1 format from my streaming services, and although the HDMI standard for eARC allows for a lossless Dolby Atmos stream, no services are yet providing it.
My goal is to get the highest possible audio quality from my new Samsung QN75QN90AAFXZA (QN90A 75" Samsung Neo QLED 4K Smart TV 2021) streaming apps on my home theater system?
I understand that today most (if not all?) streaming services deliver, at best, lossy Dolby Digital Plus and possibly some Atmos metadata. So today, the highest possible audio quality wont' be lossless Dolby TrueHD or DTS Master Audio, or lossless Dolby Atmos. For lossless, I need UHD Blu-Ray. But that is not the question here.
The Samsung QN90A has 4 HDMI ports: #1 labeled "HDMI", #2 labeled "HDMI", #3 labeled "HDMI/eARC", #4 labeled "HDMI/Game". The owners' manual is not very precise on what each of these ports can or cannot do. The new Samsung television is a Smart TV, and so it has the usual plethora of Apps, including, for example, Netflix. I've updated my Netflix account to 4K/UHD. Many of the Netflix titles available for streaming provide a Dolby Amos streaming audio sound track.
I use a Denon AVR-A100 receiver. According to the manual, "You can connect up to seven HDMI-compatible devices to the unit.
This unit supports the following HDMI functions:
• 3D
• Deep Color
• Auto Lip Sync
• x.v.Color, sYCC601 color, Adobe RGB color, Adobe YCC601 color
• High definition digital audio format
• ARC (Audio Return Channel)
• Content Type
• CEC (HDMI control)"
And later in the manual, it goes on, "About ARC (Audio Return Channel) function
The Audio Return Channel in HDMI 1.4a enables a TV, via a single HDMI cable, to send audio data 'upstream' to this unit.
NOTE
• To enable the ARC function, set 'HDMI Control' – 'Control' to 'ON'
• The ARC function cannot use the HDMI MONITOR 1 and HDMI MONITOR 2 terminals simultaneously.
Perform the 'HDMI Control' – 'Control Monitor' setting in accordance with a TV that supports the ARC function and HDMI MONITOR terminal in this unit.
• When connecting a TV that does not support the ARC function, a separate connection using an audio cable is required. In this case, refer to 'Connecting a TV' for the connection method."
I've setup a 9.2 speaker arrangement and am very satisfied with the sound. I would love to get 7.1 Dolby Digital Plus from my streaming services. It isn't lossless, but when I want lossless, I will play a physical disc.
The AVR-A100 also has an optical SPDIF input. My previous television (monitor) only had SPDIF output, and I used that whenever I watched the DTV tuner. But now I'm ready to use ARC and eARC.
Is the eARC output from the Samsung QN90A compatible with the ARC input on the Denon AVR-A100? By "compatible" I mean, will the AVR "understand" Dolby Digital Plus and ignore the Atmos metadata? Or stated a different way, the AVR-A100 HDMI Monitor #1 and #2 ports on the AVR-A100 are labeled ARC and the manual says one or the other, not both, will use ARC. I'm satisfied with that, I only have one Samsung QN90A. But the AVR-A100 was manufactured prior to eARC. Can it decode an eARC stream from the television?