No, not likely. The Sonos is looking for an ARC or eARC signal. This is created by the TV set, not the source device, so putting in a splitter won’t get you the ARC signal needed. 

A couple of things. I’d check the software on your TV and make sure it’s been updated, then I’d power cycle the TV by unplugging it from the wall for at least 5 minutes. Make sure then Beam is connected to that HDMI port that says ARC. It should work at that point for any HDMI input to the TV, but not other inputs (like analog inputs)

If you wanted to go the “splitter’ route, there are three (maybe more now) devices that will create the ARC/eARC signal for you, but they are semi expensive, at least when compared to a ‘normal’ HDMI splitter. 

There is the HD Fury Arcana, the Feintech VAX04101k, and the latest, is the OREI HDA-935. You can also order from those links from the companies directly, or check your local retailers for availability. Amazon may carry some, depending on location.

Is HDMI-CEC (Easylink in Philips speak) turned on in your TV settings? 

The TV is Philips 55PUT6400/12 and its on the latest possible update and the Easylink is turned on.

I get positive confirmation from Sonos (via Sonos app), that the TV is connectied and visible via HDMI Arc, but no sound is played :( 

And I tried the restart and unplugging for 5 min.

Might be worth spending the effort to call Sonos Support directly to discuss it, at least before you spend money on another potential solution…and a new TV is always an option. 

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.