Check X10 website for re-transmitters. If you have good wifi, use Apple Airport, or TV or other product. They will let you transmit to another amp/speaker set, or another TV
Well developed open source streaming software for wired or wireless lan. Very high quality audio. Have used for years. See: http://forums.slimdevices.com/ Also click on 'Products' at the top of the page.
A good place to get an overview is their Wiki at http://wiki.slimdevices.com/index.php/Main_Page
Players are now sold by Logitech who bought Slimdevices and can also be found on EBay.