Do you like your audio now?
Keep in mind 'vintage' speakers tend to be from the 60's. I'm not sure if these are what you have, but this is what I get when I look for B&W CM1 speakers:
I don't think the Sonos stuff is anything of an upgrade. You have a decent set of speakers and receiver and the rest. Do you have it connected to a TV, or are you just using it for audio listening? Sonos kind of works with a TV, but it's a long way from an AV receiver.
Do you use a universal remote to control things? If not, why?
I would get a Sonos Port and put it on your Denon and call it done. Especially if you are using Sonos elsewhere in your home.
Sonos is a expensive solution to whole house audio and they really don't have any really high end gear. Plus, it can be expensive to get things setup for only decent audio quality.