[villagetinker]

As noted above the voltage at the speakers is very low, zero when the system is off, and very low when on. I agree with looking into a wireless system as this would eliminate the need for hiding the wires. I have not used the Sonos system so I have no opinion.
On a side note, I have not had any good luck with surround sound systems since my really nice Pioneer system died. There seems to be some problems with the digital signals from the TV to the surround sound systems, therefore I also agree with getting a system installed by a professional.
One word of caution if your TV is older you may have more problems with surround sound as the specs have changed over the years, and I believe this is one of the reasons that I am still currently having problems, with a Hisense TV and a Sony surround system, both less than 2 years old but different manufacturers, and possibly slightly different version of the specs.