I'm actually in the same boat as Bridgeman was here, specifically needing to replace two 600W Carvins in a homemade cab.
Any particular reason why you suggest the Kappalites, though they are on my short list, over legends or peavey black widows or any in the $90 - $190 price range?
And would you suggest 4ohm or 8ohm speakers? I did not install a crossover and have each speaker wired independently to its own jack. I know this removes the chance of adding another cabinet, but I don't require the use of 10" or other speakers.
Also, I play a Genz Benz shuttle 6.0 with two speakon jacks, each rated 375W at 4ohms and 600W at 8ohms. The cabinet I've been using is homemade with 2 Carvin 600W speakers, though I need to double check the ohms, I seem to remember them being 4ohms.
I haven't opened the cab yet, but last weekend my amp was provided as the bass backline amp for an all day festival with heat reaching upwards of 106 degrees. Im not certain at exactly what time, but one speaker cutoff completely, as if dead, and the other still played loudly. Upon testing it at the end of the day, I realized the working speaker plays at full volume, but emits a low buzz, almost like a hint of overdrive.
I plan to run some diagnostic checks in an attempt to more clearly define each speakers condition and hopefully figure out what possibly caused this to happen because I've used my head and cab for other all day events without issue. Regardless, I have been interested in getting new speakers for a while and this helps place it higher on the priority list.
Thank you for any information or advice anyone may be able to give. My knowledge is limited in this area of gear and learning more about it has been extremely helpful in better understanding my sound and hopefully what I'll be able to do with it to improve it.