Simple HDMI -- Is there a way to split video and HDMI ARC?

Congratulations on the upgrade and thumbs up on the projector. Awesome little device. 
 

I think the HDMI out on the connector box should carry both sound and video. If that is the case, everything should work if you simply hook up the AMP to the HDMI out. The audio-return thing shouldn’t be relevant in that setup. 
 

If it doesn’t carry sound but only video, I think the easiest setup would be to split the signal from whatever you are connecting to the Projector’s connector box. I assume you have an Apple TV or something else hooked up to it?

If so, you can simply split the HDMI from that unit. One output will go to the projector and the other to the AMP.  It shouldn’t matter that the AMP receives both sound and video via HDMI - as long as it gets sound. 
 

Other than that, you can split a HDMI signal to video and optical and then you can get a HDMI-to-optical single for the AMP. You can get that on the Sonos website. 
 

The HDMI out will probably not work with the Beam as it is not listed as HDMI-ARC. You’ll need an adapter to extract the audio as optical, then feed that to the Beam via its adapter.

Or use the optical output of the (unspecified) source device.

And to add on to that, source devices such as DVD and Blu-ray players, game consoles, cable and satellite boxes generally don’t create an HDMI-ARC signal at all. The electronics that create that signal is in the receiver, i.e the television, which takes the normal HDMI audio channel and returns it back out, hence the name Audio Return Channel. 
 

I do understand that the ARC stands for audio return. My understanding being that the tv would send any audio it receives and generates through the HDMI-ARC. Meaning that the port serves as both a normal input for video and audio and output for audio. Naturally, using a normal HDMI from a tv would not work, because these are inputs rather than outputs. 
 

I just assumed that the Beam and AMP would be able to pick up any audio from an HDMI-signal, so if a signal carrying video and audio was split in two, one could go to the Amp and the other to the projector. Surprised to learn that it is not the case.

Must try to hook up something directly to my Beam later just to “see” it with my own ears - but for now I stand corrected :)

As I understand it The Beam and the Amp use HDMI-ARC from a TV because that’s the only HDMI on a TV that’s not only an input (only used for a test image from my Beam) but also an output. If you connect a normal HDMI-output from, say, DVD-player tot a splitter and send the signal from the splitter to the beamer and to the Amp, you should have sound on the Amp. Is there something wrong with my reasonong?

Well the normal audio on HDMI and audio coming through ARC are actually different channels.  The can also even be different codecs in some cases.  And the HDMI port on the Amp and Beam are actually HDMI outputs, generating a screensaver on your TV.  Not sure if you can make a port operate as both an HDMI input and output.  Point being that there would be some additional development/testing for this to work both ways.

Perhaps the main reason Sonos didn’t implement connecting audio this way is to avoid confusion about how to setup Sonos.  Most people are not going to want to use a splitter, which is really the only way this other method would work since Sonos doesn’t have a 2nd HDMI port to pass video to a TV or projector.  Besides, HDMI-ARC or optical from the TV is the only way to get audio from TV smart apps.

Depends on what you mean by ‘signal’.  If you mean an optical connection then yes.  HDMI, then no.  HDMI-ARC doesn’t really sense for that connection either.

Yes, unfortunately, there is.

Unless the splitter has the technology built in it to ‘reflect’ the audio signal like the TV has, that won’t work. There is no HDMI-ARC signal in a normal HDMI feed.

OK. So ARC is technically different from the sound that comes with an image? 

Perhaps think of it as highway with many lanes (channels), and cars are equivalent to video, while trucks are equivalent to audio.   For a normal HDMI connection, all lanes going the same direction with some of them for cars only (video) and others for trucks (audio).  There is also a telephone wire going right alongside the highway for small two way communication….CEC (Consumer Electronic Commands) commands.  It’s the teephone wire that sends commands to devices to turn on/off, change volume etc.

For a connection using HDMI-ARC, you still have the same lanes for cars and truck going in the same direction, and you still have the telephone wire in place.  But you also have some additional truck only (audio) lanes going in the opposite direction.

When you have a Sonos Beam or Amp connected to your TV,  The Beam (technically HDMI output)  is sending out cars (video, in the form of a screensaver image) to the TV using the lanes (channels) describing above.  It could send out trucks as well, but does not.  It is using the telephone wire to communciate with the TV.  And it’s receiving trucks from the ARC lanes.  On the other end, the TV (technically HDMI input)  is receive cars (the screensaver, which it does not need to display) and trucks (audio,Sonos doesn’t send any).  It communicates with Sonos through the telephone line, telling it to change volume, receiving turn off commands, learning what codecs it can send, etc.  And the TV sends out trucks in the ARC lanes.

So why can’t the beam or amp get audio through normal HDMI?  Because it’s an HDMI output, not an input.  Because the flow of trucks on those lanes are supposed to go in the other direction..