DJM 900 Nexus - what kind of signal is the digital master output?

Hello, I'm trying to hook up the DJM 900 nexus to a sonos beam. I know it sounds weird, but this is where I am at until I can pickup some decent monitors.

I've tried to browse through the manual, but I can't find anything the describes that digital master output signal. But my guess would be that it is plain stereo?

I've asked for help over at the sonos community: https://en.community.sonos.com/ask-a-question-228987/pioneer-djm-900nxs-digital-output-to-sonos-beam-6861427?postid=16555664#post16555664 but given that none of us really understand what the output from the pioneer mixer is, we can't come to any closer to a solution.

Any help, ideas or info would be highly appreciated ! :)