A Sonos Port? Depends on what kind of output is available on the projector. 

Hi.  What wireless technology are you planning to use?  Bluetooth?  Were you panning on getting a Bluetooth receiver for the 5s?  What will you be transmitting from?  What video / audio sources will you be playing?

The 5s are not really designed for audio - visual applications, and this whole thing sounds unpromising to me, if I’m honest.

Thanks for the replies. Figured it wouldn't be that straight forward. Will be transmitting from an Optoma HD143X. I’m guessing bluetooth is the best option if at all. 

It is generally best not to run the audio through the projector at all, but to split it off to the Sonos speaker (preferably one designed for AV applications like the Beam or Arc), with the video sent to the projector.  

There are several threads on here dealing with these sorts of issues (see, for example, ‘Related Topics’ on this page), and i suggest you do a bit of digging through these.