I have a Control4 system in my current rental home. I honestly can’t use it at all, the previous renter didn’t leave it set up, and I tried to get a local installer to come out and hook it up, and show me how to use it to control various lights, cameras and thermostats. The information I got from the installer (recommended by Control4) was not to waste my time, rip it out, and replace it with something else that works via wifi, not wired. They would not take my money to come out and “fix” things. 

I’m not really sure how that system is supposed to work with Sonos, since I’ve never had it running, but in all honesty, I’m just as happy with using the Sonos controllers on my iPads/iPhone and Mac, and running SonosNet. 

If I owned this property, I’d replace the lighting, the thermostat and anything else I could with something other than Control4. In the past, I’ve used the Nest products (before purchase by Google) to great affect, there’s a lot to be said for replacing the camera out front, the thermostat, and anything else that would normally be controlled by Control4 with something more up to date, and more accessible on non-specific hardware. 

Take this with a grain of salt, I’m still bitter over the fact that I rented this place under the understanding it was currently “wired for automation”, which I suppose it is….but not usable. 

I don’t know much about Control4, but as you already have speakers, you could just buy some Sonos Amps and wire them to your existing speakers.

I am soon moving to a house with built-in speakers but I am cheap, so I got a Connect:Amp Gen 2 on eBay to drive two pairs (in parallel). (The others will have to wait for now).

SONOS is a music system, not a control system. Control4 is a formal control system for most things that can be controlled by a 3rd party. I’m not a Control4 user, but it seems to me that you are locked to a specific dealer for support.

You can search for “Control4 and Sonos” to get opinions on the Control4 SONOS integration.