Coach,

It was late and I quickly skimmed over your post so if I had misunderstood what you were proposing to, I apologize. On 10 vs 12, while I like the two 10w0s I had, the single kappa 12 I have now is just as good. Now, if I had a amp that is just as good as I did with the 10s, the 12 might be even better. Regardless, I think based on what you described a single 12 is probably best... if there is enough air volume. The kappa, for example, requires 1 cubic foot. I don't think there is enough there for two 10s with their own chambers... is there? A panel designed to take a 12 would be great since I already have one... though, if it isn't possible a dual voice coil 10 might be the way to go. Perhaps you can make your design be compatible for both 10 or 12 via an add-on adpater ring for those who perfer using a single 10. Just an idea.

Good luck with your project.