Hi. You can play CDs to the rest of your system by grouping to the Beam and (if desired) muting the Beam.

I don't think Sonos can plqy SACD formatted disks. 

I don't really understand the "TV volume is fixed" bit

How do I do that with my current setup? Or do I need to buy something else?

This is the error message that my TV displays whenever I try to change the volume using the remote. My HDMI switch is not ARC-compatible, so I must use the optical output and the Sonos converter on the TV. Same for my CD player, I had to buy another converter and use its optical output although it has a non-ARC HDMI output.

Get a Blu-ray player. It can play audio CDs too. Connect the Beam to your TV’s HDMI ARC port. This will allow you to control the Beam’s volume using the TV remote. Connect the Blu-ray player to any of the TV’s other HDMI ports. Then set up two Play:1s to act as surround speakers for the Beam. 
 

NOTE: Depending on your TV model, you may or may not be able to play 5.1 audio from Blu-ray discs. Your TV must support Dolby Digital 5.1 or DTS Digital Surround 5.1 pass through.

GuitarSuperstar: thanks, I’ll try that. Does this mean the TV will need to be on if I want to play CDs?

Yes, CD’s and DVD’s will play through the TV’s HDMI connection.

That’s far from ideal then.

On the other hand: my TV has an ARC port, but the CD player only has an HDMI output and an optical one. Isn’t there an HDMI switch with ARC capabilities that would accept both connections (i.e. ARC and non-ARC)?

Or do I need to buy a Blu-Ray player with an ARC output and a switch that only accepts ARC connections (surely that must exist, in the event that no “mixed inputs” switch exists)?

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

But it has just occurred to me that the Beam will not synch perfectly the other speakers  and so may have to be muted

Normally, an input device, such as a cable box, DVD, etc., sends audio and video to a TV or A/V receiver. An HDMI ARC connection allows the TV to send audio back to the A/V receiver when the viewer is watching a TV App. Regular HDMI audio an HDMI ARC audio use a different set of connector pins. The A/V receiver and TV chipsets need to sort this out.

Supporting HDMI ARC connections on input devices doesn’t make much sense because one would rarely need to send audio to a DVD player, for example.

In the specific case of a SONOS soundbar there is some rational for allowing switching DVD audio output to the ARC pins, however, this would create numerous user interface complications. For example, how would the user control the DVD player if there is no video? Yes, the DVD player manufacturer could develop a controller App, but this would be a rather expensive project, simply to support a few SONOS users who want to connect their DVD player directly to their soundbar. The DVD controller App would need to support phones/pads/PC and Mac computers of various generations.

For use with CD players Sonos produces the Port. I use a Connect (predecessor to the Port) for exactly this purpose. Any solution that runs via the TV would bring the need to have the TV turned on.

Oddly enough, groups work fine when the switch’s input is set to TV: multiple and global controls appear and there’s no delay at all. But as soon as I switch the input to the CD player, the only sound controls that appear are the Beam’s …

This is my expectation. Is this creating an issue for you?

Yes, I’d like to be able to take advantage of my setup for playing my discs in the same way. If the only way to achieve that is to buy a > €400 Port / Connect as suggested above, then so be it. I’ll live with my current setup and just play CDs through the Beam.

But do you have an explanation for this behaviour? Given that both inputs are optical outs converted to HDMI entering the same switch, I don’t understand the difference in treatment by the system.

I’m not fully understanding your issue. Are you able to listen to CD’s using your current connections?

Yes I am. I just want to be able to have the sound come out on multiple speakers. This works when the TV is the source (groups are active and everything), but not when the CD player is. I use a switch similar to this one (couldn’t find the exact same model anymore):

https://www.amazon.com/Splitter-Tekholy-Aluminum-Bi-Directional-Switcher-Splitter/dp/B09CDNNZNM/ref=sr_1_6?crid=3VPSO25VB4A50&keywords=hdmi+switch&qid=1669545320&sprefix=hdmi+switch%2Caps%2C175&sr=8-6

Are the “multiple speakers” other SONOS Rooms or are they surround speakers bonded to BEAM? 

These are Sonos Ones and Plays, connected through the network and grouped with the Beam using the app.

Well, nevermind. Restarted the system and now everything works as I wanted. The mysteries of technology ...

The above discussion is helpful and a little confusing.  I have the same need to connect a CD player to a system where a Sonos Amp is powering Sonus faber speakers.  A Samsung 55” 90Q tv is connected to the Sonos eArc and works beautifully for tv sound through the speakers.  There is not need for a center channel as the phantom center channel created by the Sonos Amp is terrific and the clarity is better than my previous Sonos Arc.  Now, I want to add a CD player.  I was advised by technician at SVS (who sold me my 12 gauge speaker cables), that rather than adding a CD player to the line in, to get a blu-ray player which also plays CDs.  Sony makes good model x700M and x800Ms that have two HDMI outs as well as a coaxial cable out.  The coaxial cable out would be perfect for the CDs, except Sonos doesn’t have a coaxial input and doesn’t pass through 24hz-192khz.  It reconverts any CD player’s analogue out back into digital and then does its own “hidden” thing to reconvert to analogue.   My question is:

1. Can I use the HDMI video/audio channel connected to the tv for just DVD video watching and connect a second HDMI to the TV from the blu-ray player’s “Audio only” output just for the CDs.
2. If yes, can I listen to CDs with the tv off, or does it have to be on at all times to listen to the CDs through Sonos Amp/Sonus faber speakers.
3. Panasonic makes a blu-ray player with a 2 channel line out - could that be used for just the CD playing (connecting directly to the Sonos Amp line in?) and then the video would be HDMI to the TV?  Or would it be better to use the Panasonic’s second HDMI out to the tv, same as for the sony.  This model is higher end and allows connections directy to seven-channel home theatre, but it has two channel RCA out as well