Thanks
Thanks
Your Polks are probably just fine. Not hearing dialog well is (usually) not a speaker problem, it is a speaker calibration problem. The main exception is if the center speaker is damaged, like a blown tweeter. Rather than spending money on new speakers, get a Radio Shack Sound Pressure Meter and a calibration DVD like Avia of Digital Video Essentials. Also, most receivers these days have their own calibration program and microphone, but I personally prefer the meter/disc route.
I would follow the advise of the previous poster and replace your blown receiver with a new one and see how your existing speakers work after they are properly calibrated. Perhaps that old receiver was causing a problem before it died on you. If you still don't like the sound of the existing speakers then you may want to start looking for new speaker system.