I am looking at purchasing surround speakers for my setup. I currently have a Yamaha RX-V1, Paradigm Monitor 3 as mains, a JBL Northridge Center and Yamaha SWT160 Sub. My current surrounds are purely temporary. I am trying to determine if the QS8 or QS4 is my better choice. What should i be looking at to determine the defining characteristics. Thanks for the help!