Cables for Surrounds Under Carpet

I am in need of new cables to connect my Rotel amp to my B&W N805 surrounds. They need to be approx. 20 feet in length and MUST go under carpet as I am in an apartment. I am using the cv6 audioquest with dbs for fronts and center and love them. I have been using plain 10 guage cheapo wire but it allows too much interference/static through. Any suggestions. I would like to biwire them as well for the speakers. Any help/suggestions are appreciated.