Is it at all possible to swap in another 15" or 18" driver in my Theater 4s to 1) gain a bit more efficiency and 2) to gain a bit more transparency/ detail. I don't care as much about bass extension but do want to enhance the dynamic responce, both macro and micro. I was looking at the new Eminence specs and it seems the Delta 15 is not as efficient as was once thought though they list the Kappa 15" models and the Kappa pro 15" as more efficient and more in line with the design goals of the Theater 4. I'm guessing this has been hash about here before but what advice can you give on this subject. Id love to be able to re-use my Theater 4 cabinets since I don't have much time anymore for wood working projects.
Thanks for any help on this!

Garland