I may be wrong, but it depends on how many speakers you're running...meaning, are you doing a 5.1 set up or a 7.1. In 5.1, you'll only have "surround" (meaning speakers connected to the surround terminals on your reciever/preamp) for all surround information. However, if you have 7 speakers and a 7.1 set up, you'll hook up speakers to both the surround inputs and the surround rear for 7 channels of output...your receiver/preamp will decode and send information to the 7 separate channels as opposed to only 5. If you only have 5, you'll want your speakers connect to the "surround" terminals and not the "surround rear."