This.
To be completely hones, I do not have the experience to know to what extent the THX rating on the Mono-Mono 12" Sub signifies in terms of comparing it, perhaps, to a non-THX 15" Sub.
We have seen examples of smaller drivers performing at least on par with larger divers in the past, so is it unreasonable to consider that a very well designed 12" could hang with a well designed 15" SUB? I don't think so, necessarily.
My X-13s earned their THX rating as a Singe Unit. I think it might have been the first Single Sub to garner that mark. I do not know if the Mono-Mono did so as single units or not. Either way, both are Claridy designs.
When I was shopping, Shady mentioned that the Mono 15" would outperform the X-13 in some metrics.
Regardless, definitely a great point, Bill. And likewise, i don't have a dog in this show either.