I didn't know and at the time of my posting I didn't have either the Sonos or the M80s - that's why I asked

Shipping from Sonos and Axiom only takes 1 day (both are amazing companies that way). I confirmed with Sonos that they can drive (1 pair only) of 4 ohm speakers.

I couldn't be more pleased with both the M80's and the Sonos.