I wouldn't think in terms of the wattage as it doesn't mean a lot to begin with on its own let alone compare well on its own....you mean amp power or that is what your speakers are rated for? I see a manaul for your Mission 710 saying max 80w, didn't find anything for the Paradigm Phantom.
I wouldn't buy Sonos speakers at all myself. For fairly inexpensive active speakers might look at the JBL 308, if you want to spend some more the 708 would be good, too; both speakers have 8" mid-bass drivers. Integrating subs with active speakers can be difficult....altho JBL does sell matching subs (at least for the 3xx series, the 310S, not sure about the 7xx series) with an actual crossover between sub/speaker.