I have a Pioneer VSX-D711 A/V 5.1 receiver and two old Pioneer bookshelf speakers with 12" woofers. What Axiom speakers whould you purchase first to build a 5.1 system. I am looking at the M22ti for mains, VP150 center,QS4, and EP125 sub. My room that I am setting up my sytem about 20'x20'. Do you think I need to upgrade my main speakers first? Do you think the EP125 is going to be large enough for a room this size? Thanks,