Hi.  Like all Sonos HT products, the Arc is designed to replace an AVR, not work alongside it, so I can’t see how what you propose can possibly work.  Unless the Denon is just acting as a large, expensive switch?

Thanks for your answer
You absolutely right in this case the AVR is just a hdmi-splitter but I can’t find any other options to creating a fully compatible Dolby Atmos HT configuration with a projector.
I'm not an expert and may be other people using different approach to reach this... Could someone give me advice on how to do it?

Yes I’m out of my depth here, but hopefully someone else will come along who can help.

Unfortunately, that’s not going to work.  ARC stands for Audio Return Channel, meaning audio is returned from an HDMI input back to an HDMI output.  The HDMI port on the Arc is actually an HDMI output.  Your design is to connect your AVR HDMI output to the Arc’s HDMI output...which won’t work.

Hmm... that means Sonos Arc only works with Dolby Atmos through the returned audio signal from TV and I have no chance of building HT based on the projector, Sonos Arc and Apple TV with Dolby Atmos support, right? It really disappoint (

As of now, yes, that’s the case.  There may be a project out there that is ARC/eARC capable, but I’m not aware of it.  Likewise, there may be an HDMI switch/extractor of sorts that can generate an ARC/eARC signal from normal HDMI, but I’m not aware of it.

Thanks for the answer. 
Apparently will be better to give up idea of building Dolby Atmos HT and not spend money on Sonos Arc (
Sonos Playbar with DD 5.1 through the optical audio is still reasonable solution for now if you want to watch video from a projector...

When you have two HDMI outputs, and if the receiver can dual output the same audio/video.. why can’t one be routed to the projector and other to the Sonos Arc? What do you mean “The HDMI port on the Arc is actually an HDMI output”? Sonos arc has HDMI input which needs to be connected to HDMI from a TV, what if we connect to receiver in this case? 

Because the two “outputs” on the receiver are both standard HDMI channels, both video and audio. Neither of them contain the “ARC” requirement that Sonos is looking for, that’s usually reserved for the TV set to create. 

HDMI can be a two way stream, as you advance through the features. Initially, it was one way, from source to monitor. Eventually, it became two way, with CEC and ARC being added, in which case a different signal gets sent back from the monitor on separate pins on the HDMI cable. Since the receiver doesn’t know to send the audio on these other pins, it only sends them on the normal pins associated with HDMI. It requires the electronics in the TV to “reflect” the signal on the Audio Return Channel pins. 

I can confirm that you can’t connect a Sonos arc to an A/V receiver that is e-arc compatible. I have a Sony str 1080 with full e-arc support with an e-arc HDMI port. The Sonos arc doesn’t recognise the signal.

i made the expensive  mistake of thinking that the Sonos arc will work with A/V receivers - it doesn’t. 
 

I now use my Sonos arc as an AirPlay 2 device - sound is pretty meh. 
 

If you have an a/v receiver stay away from the Sonos arc.

Thanks for your confirmation! It’s sad but expected

I would hope that in the future the new devices from Sonos will support additional interfaces

I know this is an older thread, but we need more cases like this on the internet for Google research.  I wish my case were out there more, but it being week 2 of Xbox Series X being out there I had no help.

One more point of confirmation here that it doesn’t work.

My Involved Equipment:

-Xbox Series X

-Sony XBR65X900F

-Sonos Arc

-HDMI splitter

Intended Use Case (ideally)

Xbox (video + Dolby TrueHD audio signal) → TV

TV via eARC → Soundbar which would send out uncompressed awesomeness.

Problem:

Since my TV didn’t support eARC, it could not support Dolby TrueHD with Atmos riding along that codec.

Attempted Solution:

Xbox (video + Dolby TrueHD audio signal) → HDMI splitter

HDMI splitter (output 1) → Video to TV 

HDMI splitter (output 2) → Audio to Sonos Arc

Why It Failed:
Two reasons:

1. In the setup for Sonos Arc, it will let you know when it no longer detects a legit HDMI ARC or eARC port.  If at any time it detects you’re not using one, it simply stops working for HDMI.  It still works as a standard Sonos speaker, but not for HDMI.
2. Video mode switching was going crazy as the one input HDMI was looking at BOTH outgoing HDMIs for video mode information and my TV was going nuts.