5.1 Surround with Projector and AVR

It really is that simple....although you'd need to be sure that whichever device is sending the signal through that optical cable is locked down to dolby digital (at least for now, who knows about the upcoming device that we're not talking about). So basically, all of that wonderful 7.2 that can be done by that Denon goes to waste.

But everything that your client has, the Apple TV, the Samsung blu-ray player, every source will need to be locked down via it's audio settings to send only dolby digital. For instance, if the blu-ray player were to send a DTS signal to the AVR, and the AVR passed it without modifying it to Dolby Digital, there would be no sound coming from the Sonos speakers, and you'd be getting an irate call from your client.

At the end of the day, the "hub" of the 5.1 experience from Sonos is the Playbar, which gets its A/V sound from the optical connection, and then disburses it on it's own network (called SonosNet) to the sub and the surrounds. The added benefit is that all those devices will also be connected to the internet during setup, and be able to do all of the normal streaming music stuff, be it from a local drive/NAS, or across the internet (assuming they have an internet connection and a router to connect to. Would still work as a TV sound device without any further connections).

For what it's worth, you should know (and perhaps already do) that there's almost no reason to put a proper AV receiver in this setup and, based on a quick look at the input/output list of that one, one very good reason not to. That reason is that the model you mentioned (along with nearly all AV receivers) doesn't appear to have an optical output, which is required to run audio to the Playbar. Beyond that, there's just no reason to have an expensive device meant to decode audio signals and power un-powered speakers effectively acting as a hub and pass-through for what is ultimately a stand-alone system.

More appropriate would be any one of a number of fairly cheap HDMI splitters that have an optical output. Monoprice has at least one that works perfectly, but there are more expensive options if you're reluctant to put something cheap-sounding/feeling like that in a client setup.

The issues, as Airgetlam pointed out, will then be around setting the proper audio output format. I believe the Apple TV can be set to output nothing "over" Dolby Digital (i.e. not Dolby Digital Plus and DTS). I know the old one could, but have not tried the newer one. You would need to make sure that the blu-ray player has that same capability. Many say that they do, but from what I can tell, it's hit or miss and many that will transcode DTS to DD will only then output that from their optical output, not HDMI.

The reason for not wanting anything beyond Dolby Digital is that DD+ and DTS cannot travel over optical*, so your device will either "dumb down" the sound to stereo, or will not send out an audio signal at all.

To be perfectly clear, everything will for the most part still "work" even if the audio formats aren't right and you're only getting stereo delivered to the Playbar. The Playbar is designed to turn a stereo signal into simulated surround sound and does a good enough job that many people don't care (and don't know) that they aren't getting the original multi-channel track. That said, many on here don't like the idea of making such a big investment in home theater and then not getting proper surround sound.

*I actually forget if DTS can travel over optical, but even if it can, the Playbar can't decode it, so the issue remains.

Just to agree with User385289, in general, but I was thinking of the receiver more as an expensive switch device for the various video feeds, sending the signals on to the projector. I did not look up any of the devices, but most projectors that I'm familiar with have a single HDMI input, and occasionally composite inputs. So I was thinking in order to drive multiple inputs to the projector, the reason for the AVR to exist was to be the switch. That being said, as you say, there are a lot of less expensive ways to do that.

But I'm not a systems designer, or a home A/V installer. 🙂

Bioguy's set up is something I am exploring and I really appreciate Airgetlam and User385289's response. Is there a limit to how long an optical cable can stretch before you might experience degradation? I am thinking my projector will sit between 12-15 feet away from the Playbar. My question might give it away, but I am super new to trying to set up the home theatre bit (which is only 1 part of the multi-room audio set up I am exploring).