Good for you Ronno, THAT is the way to test a subwoofer. I'm not sure what you would consider "a clear step up," but listening is the way to see if any subwoofer would provide it. I suspect the PB12-Plus 2 will play a little louder and go a little lower, but I think you'll find the EP500's frequency response to be smoother and more refined. For my tastes, it plays loud ENOUGH, and plays low ENOUGH. Only you can decide if that is ENOUGH for you. Good hunting.
Do I understand you correctly? Are you considering keeping both subs? Not a bad idea, if it is within your budget. If you are, you should seek out Jakeman, here on the forum. He uses one 600, two 500s, AND a PB Ultra. He has things set up so the Ultra handles the really low stuff, where it has the edge, and the Axioms handle things above a certain frequency (20Hz? 25Hz?, I'm not sure where he crosses them), where they really shine. Anyway, he would be able to give you some great ideas on how to set up two subwoofers.
