Hi, you haven't thought about passive bi-amping using the crossover of the cornwall IV. You could put an amp with adjustable gain, the parasound a23 comes to mind, to drive only the klipsch woofers, perhaps looking for it used, and thus dose the energy of the 15" as you prefer, just to experiment. I don't know, however, if the Primaluna in your possession has a pre-out to which you could connect it. While on the horns you could keep your Primaluna. Incidentally when klipsch switched from chorus to chorus II, closed the reflex holes and added a rear passive woofer, leaving the dimensions of the cabinet unchanged, as well as switching to tractrix horns. I have the Cornwall III and I wanted to do the same thing, that is to close the front reflex and add an 18" woofer at the back. I haven't found any craftsman in the sector willing to make the modification. Many years ago I owned forte' II, that type of bass they gave off and that monstrous drop in hertz they had were fantastic, different from the forte IV I recently heard in the shop... Who knows if that modification would better suit the Cornwall III or the IV (at least I'd look for it used). I translated with Google, sorry for the mistakes