No, there is only one source going to all 3 pairs.  You could wire in manual wall mounted volume controls, but it cannot be done from the app.

Thanks for the quick reply.  Do you have any recommendations for wall mounted volume controls?  Thanks again.

No, but with 3 pairs, you should get the ones that are impedance matching, because 3 pairs of anything but the Sonance models sold by Sonos will put the Amp into fault mode because impedance is too low.

Thanks.  I am planning to buy the Sonos in-ceiling and outdoor speakers.  Hence my ability to power three pairs with one amp.  Thanks again.

Just an extra note, which jgatie alluded to….but the in-ceiling and outdoor speakers sold in the Sonos shop are not made by Sonos, but in fact made by a company called Sonance, which Sonos has a marketing agreement with. 

www.sonance.com