I am looking at adding a rear back speaker for my setup for DTS-ES. I currently am running 2 dipolar surrounds. My question: Can I just buy a monopole rear for this and expect it to sound good? I dont see how I would add a dipole speaker, as they are left/right specific. If I do add a monopole, do I need to switch my other rears to monopoles? Any opinions or experiences would be helpful. My relavent specs: Pioneer VSX-D850S reciever Polk FXi50 rears Thanks!!