u/Good_Possibility

After a ton of research on different threads and over a year of thinking it wasn't possible, I finally got it to work. Sharing this setup for anyone else who has Sonos and wants to be able to use their DJ table on it.

It hinges on having a Sonos soundbar. I have the Arc, but I suspect it might work with other Sonos soundbars that have an HDMI input.

1. Run the RCA output cables from the deck to an Analog to Digital Audio converter.
2. Use the Optical to HDMI converter cable that comes with the Sonos soundbar.
3. Plug the HDMI cable into the soundbar and into the Optical to HDMI converter cable.
4. Plug in the Analog to Digital converter to the power source and play some music. With luck, it will work right off the bat. If not, no worries, you have to trick the Sonos into thinking it's hooked up to a TV. You may have to re-run the Sonos TV Setup. In your Sonos app, go to settings->system -> (your speaker or room) -> TV Setup. This fixed any issues I had. Make sure to keep playing music so you know when it's working.
5. Once it's working on the soundbar, you can select that input to play on other speakers you have as well.

Hope this helps someone. I searched everywhere and couldn't find this solution detailed. People just say you have to deal with the latency.