They seem almost identical to me, so I don't know which one to get. It says that the DAV-HDX275 is offering an option to add a pair of rear wireless speakers and an S-AIR transmitter with S-AIR Air Stations, the DAV-HDX277WC model includes one S-AIR Air Station receiver/speaker with an option to add a rear wireless speakers, and the DAV-HDX279W model includes the rear wireless speakers with an option to add S-AIR Air Station receiver/speakers for multi-room audio. The DAV-HDX275 is $300 while the other two are $400. What do you recommend?