The PB12 has a bump in the frequency response around 50 - 60hz, which I found a little annoying as it made the sub sound more like a car subwoofer.
One of the compromise tricks uses to give a sub more slam and apparent bass because it does not have the real low stuff for movies.
Jay. Its interesting that you now prefer the EP500. I believe that extra texture you like is actually harmonic distortion. Ilka's measurements clearly showed that there is quite a bit more distortion in the EP500/600 than the PB13. It is also interesting just how subtle everyone finds the difference.
