Hi. I have a room I'd like to wire with 4 bookshelf-sized speakers (one mounted in each corner), and, presumably, a subwoofer. Assuming I have all of the speakers and subwoofer that are the proper size for the room, what is the best set up for the wiring? There's no video input necessary, the inputs I need are an AM/FM radio, an XM satellite radio, and an auxiliary input (probably for an iPod or the like). Do I need a receiver? An amplifier? Both? Neither? How should the wiring work (i.e. speakers -> subwoofer -> receiver, etc.)? Thanks!