Rear speakers are more for a "surround" as the 5.1 is intended for. If you're listening to studio music (recorded), you should only use a 2.1 setup, if you're listening to live recordings, a 5.1 setup is what you want, for more of the "acoustical" sounds. If you absolutely want your rear speakers to play, you could plug in your rear speakers to your front speaker terminals (providing you have a terminal setup, and not an "input jack"). I have mine setup like that, but I have a kill switch on my speaker wire so I can kill the rears when I am listening to Audio CD's or other music files. Although, you can do harm to your setup's amp, as combining the speakers will change the OHM load, to either 4OHMs or 16OHMs (based on most "home" setups, as their speakers are mainly built with an 8OHM voicecoil.