The web site says “ If your TV does not have HDMI, Arc comes with the Sonos Optical Audio Adapter “ so problem solved.

Yes but then I need to pull out the soundbar, manually unplug the ARC HDMi and connect the PS4 optical > HDMI. Then when I finish the PS4, do the same thing to plug back in ARC, surely Sonos doesn’t plan for this?

Your TV has an optical output.

But the Arc doesn’t have an optical input.

https://www.sonos.com/en-us/shop/arc.html

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Sorry I dont think you understand my point. Whilst PS4 surround sound can be achieved without lag directly into the Arc via optical > hdmi adapter, it means every time I want to play PS4, I need to remove the current TV ARC HDMI that is currently plugged into the Sonos Arc for all other audio and replace it with the PS4 optical to HDMI adapter. This is not ideal as it requires manual unplugging and re-plugging devices into the soundbar whenever I want to swap devices which isnt the easiest thing to do with my setup.

Or you could just connect to the TV optical output for everything.  

But then Dolby Digital+ and Atmos will not work, which is a main feature of the Arc.

Ah, now the issue is clearer. Either you need some ugly switch solution, or get a TV which doesn’t add unnecessary delay to DD over HDMI. Or bug Samsung to fix their TV.

There currently isn’t an ‘ugly switch solution’ that swtiches between an optical or ARC connection to the Arc.  And it’s an LG TV, not Samsung.

Change the TV.