Before the changeover to the current model lineup Diamond Audio's top-end substage driver was the TDX. It is supposed to be mechanically identical to the current D9 but with somewhat differing cosmetics.
I run the TDX and feeding it 750 watts+ it sounds freggin' great.
Diamond's subs are not meant to be SPL drivers of any sort but they're accurate as can be given adequate wattage and a proper enclosure and can get plenty loud when asked to.
(//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif Don't get fooled by the rather meager wattage ratings...they'll take far beyond rated power in the right box //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif)