@last_lemming Do you have a way to measure SPLs, confirm your subjective impression? When I rebuilt my CS2.4 crossovers, I was able to compare the before and after frequency response using the SafeNoise app on my iPad and a tone glide.
BTW, not that I think this is your issue but have your tried a set-up with the speakers on the shorter wall? Either way, I suggest taking a look at the Cardas website for some placement ideas to try after you figure out your problem.