I would rather recommend a surround amplifier and passive speakers. If you only want stereo and no surround with 4 such speakers, you would have to split the signal with a Y-cable. Then you can do it like this.
So why not a true 5:1 system? The subwoofer can be installed just about anywhere. Otherwise, if the source (TV, console) has 4 front/rear L+R outputs, it's feasible since the R1280DB has 4 line inputs (photo4).