I have not heard the Cornwall IV, but I owned the Cornwall III. I prefer Forte III due to its having LESS cabinet resonance. I even preferred the Heresy III over the Cornwall III because of this reason. (The Heresy would NEED a subwoofer). That being said, I even sold the Forte III and now use slightly modified Forte II speakers. I also have a pair of slightly modified Forte I speakers that I rotate in sometimes. (the mod is Ti tweeters and Crites crossovers on both my Fortes).
I wonder if the cabinet resonance problem has been addressed on the new Cornwall IV?
I wonder if the cabinet resonance problem has been addressed on the new Cornwall IV?