They aren’t directly compatible. You’d need to introduce the sound signal into a Sonos device with a line in, using the Line Out RCA jacks on the back of the device. These would go either to a Sonos Port, or a Sonos Five, or, the unreleased Sonos Era 100 or Era 300s. Once the data is in the Sonos ecosystem, you could then play it on your PLAY:1s. If you went with a Sonos Port, you could take the Sonos signal from the Port’s Line Out and connect it to the analog input on your Marantz.
Note that the line in on any Sonos will be subject to around a 75ms delay, so if you’re playing content from the Marantz on the Sonos, it will be slightly behind the sound of the speakers connected to the Marantz. However, if you’re playing a signal from Sonos to the Marantz, all speakers would be in sync.