Hi mikei

I have a good friend who has the EP500. I have an SVS 20-39, no experience with their PB12-ISD. As between the EP500 and the SVS 20-39, I'd go with the EP500 in a heartbeat. It is an incredible subwoofer. I'd go with the QS8s instead of a second pair of M60s. The surround material in movies just doesn't justify another set of towers. The QS8s are superb surround speakers. Just my 2 cents. G'Luck!!

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.