I’d recommend a Sonos Port, which you could then connect the analog connections from the Dual Record Player (or an associated pre-amp) and get the signal into the Sonos ecosystem. Then you can “cast” the line in on the Port to play on your (Beam?) gen 2 sound bar, and any other speakers that you have.

I would not particularly try to pass that through any TV set, or even convert an analog (line level) signal to HDMI ARC, if I could avoid it. You start getting in to all sorts of odd issues, and the TV set would need to be on, and you’d likely also need to add a switch to the HDMI input, etc. Much better, IMHO, to not use the TV as your “hub” for Sonos. Use Sonos as the “hub” for your music, instead of the TV set. 

According to the data sheet that I found, there is an analog audio input for the VGA connector. From the picture, it seems that there is also a component video input that will also have an analog audio input connector. You may be able to patch the turntable through one of these audio inputs, however, these inputs might be fussy and not enable audio input unless it is accompanied by video. If this is the case, you could be creative and find a video source to satisfy the requirement. Another nag might be that the analog audio input is not be digitized and passed out through the HDMI-ARC. Finally, TV analog audio quality is notoriously poor. But, it’s cheap and only requires a few minutes to try it out.

Any SONOS unit with a Line-In (PORT, FIVE, AMP) will support the turntable, unless they are configured as surrounds.