We plan to purchase Sonos Amp, if it will do what we need...  Our house came with a Russound SDB-6.1 speaker selector, wired to 6 in-ceiling single-speakers indoors and outside.  I have no idea brand, type, or specs of the speakers.

We want to get rid of a stack of outdated equipment and get a simple solution to stream music and audio content from laptops, ipad, and/or phones.  Can we use a Sonos Amp attached to one of the 2 input ports?  

We understand that we will still need to manually use the speaker selector to turn the 6 speakers on/off, and to adjust relative volume of one speaker to another.  That said, could we adjust the Sonos volume output remotely, and wouldn’t that translate (in layman’s terms) to “more or less sound going from Sonos into Russound, equals more or less sound going into every speaker”? 

Thanks for helping an audio-amateur!