Heh….you took away the obvious answer :)

It really depends more on what the Denon AV receiver is looking for. It’s it’s an ARC (via HDMI), then you’re in some potential trouble. If it’s merely standard HMDI, in which it will strip out the audio, then you’d be fine with a standard splitter (with normal concerns about signal degradation for being split) sending a standard HDMI to the Denon, as well as the TV, and keeping the Sonos connected to the TV’s ARC port.

I’m not sure I’m overly familiar with ARC specific splitters, though. They may be out there, but it’s a relatively non-standard request, so you may have a hard time here. 

Not sure why you would want this, but the splitter should be able to relay HDMI-ARC, that uses different pins then usual HDMI. I’m also not sure if having two devices on one ARC port can be done at all. You mostly switch HDMI sources, not split them.

I think it really comes down to your sources.  Are you using TV smart apps or a connected HDMI sources (cable box, streaming box, game console, etc)?  If your using connected sources, they you should be able to connect those sources to the Denon, which could then pass the data (assuming audio is passed) to the TV, which will pass the audio to the Sonos Amp.  If your Denon doesn’t pass the audio to the TV, then you would need to have a separate splitter or matrix that passes audio/video to your Denon and TV at the same time separately.

If you want to use your TVs smart apps, I’m not sure you’ll be able to send that out via HDMI-ARC to both the Denon and Sonos amp at the same time.  You would likely need something like HDFury  Vrroom (Arcana would not be enough) or a Feintech switch.  I would be much easier to stop using the TV smart apps and use a FireTV, Roku, or whatever streaming box you prefer, instead.

The simplest way to achieve this, if your Denon allows it, would be to use RCA outputs from a Zone 2 or similar line out connection from the Denon to the RCA inputs on the Amp. Unfortunately a lot of AVRs don’t allow signals that are digital in origin to be sent over the analog outputs — but to determine that you’ll need to RTFM (or post your model number so someone else can do it for you).

If the DENON offers a Zone2 audio output, using a optical converter here might be an option. Note that many A/V receivers will not convert digital or HDMI audio sources to analog for Zone2.

Another option, which usually works, is to use the optical output available on most modern TV’s and connect this to ARC using the adapter included with ARC. This is easy enough to try. Be sure to test all of your sources and audio formats because there may be some formats that the TV will not pass through to the optical output. Unfortunately, setting the required TV options can be a confusing, poorly documented mess.

Thanks alot all - great responses.  So i left out one key piece i think.  My main source for content is my Apple TV4k.  I use this for TV (Bell Canada Fibe app) and streaming.  Should I be able to run something from the ATV to the Sonos in order to hear TV audio as a source?    Thanks

Yes, but it would be messy. I think that he best plan would be to connect the AppleTV to the TV. It’s audio will flow back to the DENON via ARC and the DENON could provide audio for SONOS. If the DENON does not properly support this and there is no need for other DENON supported inputs to be sent to SONOS, then connect AMP to the TV’s optical output port.