Depends on which Sonos hardware you have and exactly what you want to use the Melody for.

You can AirPlay from the Melody to any Sonos device that has AirPlay support.

You can wire analog-out from the melody to line-in on a Play:5 or Connect.

I have a Beam and 2 x Play One speakers, and iOS or MacOS.

How do I AirPlay from the Melody to the speakers and which app do I use to control this ?

Thanks for your help

I may have mis-spoken on AirPlay - the Melody says it supports it, but if it only supports it as a Receiver then that wont help as Sonos does only support Receive too. If the Melody supports it as a Sender, then I would assume you would use their app to Send their content to your Sonos system.

The Beam supports optical in, but the Melody doesn’t have optical out so that wont help.

I’ve never seen a non Apple device that can send an AirPlay 2 signal, only receive it.

I haven’t looked much, though. The impression I’ve carried is that Apple reserves sending for their own hardware, and only licenses the receiving side. 

Open to be corrected with evidence, though. 

So, Wikipedia suggests: “In 2016, HTC released an Android phone with Apple AirPlay streaming."10]”

But that was AirPlay, not AirPlay 2. Reading through the ‘senders’ area of the article, it’s not explicitly said that their are any other devices that can ‘send’ an AirPlay 2 signal...but it doesn’t say there isn’t, either, so I may be wrong. 

I think the Marantz can only receive an airplay signal.