I have a yamaha rxa3070 receiver with built in musiccast. I don't have the ability to run wires from the receiver to a set of surround speakers. I've been reading about musiccast but I don't understand what it is? All I want to do is add surround speakers to my receiver to give me 5.1, but I don't like that there are only two options made by yamaha that I can use. Are there other musiccast compatible wireless speakers that I can use for my surrounds?