Best answer by Chris
Sonos is going to add in a 70ms delay. When speaking through a microphone your voice is going to have a slight delay that can probably be annoying.
Mixers etc. would have to feed analog input to a Sonos analog input (Connect made for that but Connect:Amp and Play:5 also have an analog input).
If you have live speakers off mixer and then want speakers other side of room with Sonos ... again don't recommend as that will have an echo with the Sonos speakers being 70ms delay behind.
As you can see - I'm not leaning toward a use where Sonos is good for DJ'ing unless your doing simple DJ'ing like just creating a playlist and playing song request (or just using Sonos as a music source)..
I had a work event and I did hook my Sonos Connect to a couple PA speakers for music at the event. I just created a Sonos playlist and then added songs as people requested them. So I used Sonos as mearly a music source - not a method to play. That actually works. I plugged mic into the PA system and Sonos was just a music source for the PA. So if using a mixing board etc. you could use Sonos as a music source (treating it just like you would a phonograph or CD player hooked to the mixing board). That again would mean a Sonos Connect. A Sonos Connect definitely can be used as source of music for a DJ setup. But just a music source. Sonos speakers as far as playback is concerned is not a good choice.