Easiest thing to do is get a Sonos Connect and hook it to one of the available inputs on the receiver (like Tape / MD). If you don't have another available input (don't know what kind of receiver you have).
Once the Sonos Connect is hooked to the input it really works just like your CD player - but controlling it via all the sources available to you from the Sonos app.
So first thing to wade into Sonos would be get the Connect. www.sonos.com/CONNECT
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Alternate more expensive route - but I like being able to control rooms separate. You can have your existing system as above and working. But then if you want the Accustimass system to be able to play its own separate music at separate volumes you could unhook it from that receiver and hook it to a Connect:Amp (which is a Sonos receiver). That then would give you a second room in your sonos controller that you could then play the same thing to (grouped as before) but be able to change volume independently OR you could actually play completely different music in that room independently. Meaning you don't have to be playing music in one room to play music in the other or play completely different music in both rooms at the same time.
Respect the Queue (2)Move (3)Beam (1) Era100 (2)ARC (1)SonosOne (1)Playbar (4)Play5 (4)Play1 (3)Play3 (1)Port (2)Connect (1) Roam (2) Ace (1)Connect:Amp (4)Sonos Amp (1)Sub + (9) Echo + Smartthings; (2)Play)