I own a pair of PSB 6T speakers. A while back I replaced the electrolytic caps with polypropelene caps of the same value. PSB uses 100 volt caps. They are very small and not real easy to get to because they not only mount the crossover boards with the binding posts but also everything is glued together! It is time consuming because getting it all apart takes a while. The other issue is that the electrolytic caps are about 3/8" in diameter and about 3/4" long. Polypropelene caps that are the same value and the same voltage are about the size of a "C" battery, so it takes some innovation to fit it all together. When I did it, I did not really notice a difference in the bass, but the mids were clearer and the highs, which I previously thought too aggressive were now smooth and clean. While doing it, I thought "this had better be worth it", after listening and especially after the caps broke in I thought "Man; that WAS worth it". The speakers were so much more refined that PSB could practically recap the Image and do nothing else, mark up the price and market it as a higher end model. Not subtle but a pain in the ass.