DD has the best sub of all of those i believe, might be thinking of somen else its like the 9912 or somen...idk...ppi makes great amps, memphis makes good subs for the monsey ID makes good sq stuff, thats all i know lol
"The Image Dynamics ID MAX wouldn't beat the Brahma in spl, but it would still be loud and would probably have better sq." Actually, the ID Max displaces more air linearly than a Brahma and does so with the advantage of more surface area, so either sealed or ported, it has an advantage SPL wise. It has a strong motor and a tight gap, so remains controlled at high excursions, similar to a Brahma, and is also very lightweight. SQ is subjective, but really I haven't heard a single person complain about the SQ of either subwoofer, it's just what you prefer. The ID max couples better to ported enclosures if you're SPL inclined, though, due to the suspension Q. The Brahma has the advantage at high excursions, the XBL^2 motor does perform better at controlling a subwoofer at high excursion levels, the only problem with a Brahma is that it has a smaller surface area, so SPL is a little more limited even with the high linear excursion. The Resonant Engineering X.X.X. is better for overall SPL in that respect, and also works better in ported enclosures than a Brahma.
As far as the brands, it's a subjective issue, but out of them, I'd go between CDT and Dynaudio for components, all of those subs are good, but it's subjective and depends on what you want, the new PPI stuff is so-so as far as any of it, more mid level than high end.
I thought you said yourself that though you liked ID MAX's, and run one yourself, that the Brahma's and X.X.X's would probably have the advantage in SPL? Isn't the ID MAX more sq oriented? I remember you saying something like that quite a while ago, maybe I got mixed up.
The X.X.X. does, but the ID Max has more displacement than a Brahma. The ID Max doesn't come in a 15", I do remember a thread where a guy was considering a 15" Brahma vs. a 12" ID Max vs. and 15" X.X.X. I think that's where I stated that, not sure though. It is an excellent SQ subwoofer, but SPL is no problem either. The ID Max has more surface area than even the equivalent sized W7 and the X.X.X.. While high excursion is good, it mainly sees it's benefit when that subwoofer is well designed and you're comparing enclosures that allow high excursion, which would mainly be sealed or infinite baffle. In ported enclosures, SPL is more dependant upon surface area than linear excursion, as linear excursion isn't usually attained to it's full extent in ported enclosures due to the increased cone control, and ported is often chosen for SPL and SQL applications. Of course, this also correlates with the power applied and the motor strength, as some higher excursion subs have enough motor to get more excursion even in a ported box. Digital Designs subwoofers are a testiment to this, the DD 9500 series is around a 16mm x-max, but ported it takes the cake in SPL when compared to an X.X.X., W7, ID Max, Brahma, etc. X-max figures don't tell the whole story by themselves, as the x-max spec is attained by subtracting gap height from voice coil length, and dividing that by two. Any subwoofer with a long voice coil and a short gap will have a good x-max spec, but that won't necessarily mean it will achieve good results or attain it's full excursion. SPL correlates more with how well controlled the voice coil is, which relates to the percentage of the coil that remains within the magnetic gap, this can also aid the SQ in the process assuming the sub isn't designed to be a one note wonder. Subwoofers such as the Premier SPLs, Cerwin Vega Strokers, DD 9500 and 9900s, have relatively low X-max specifications, but are highly regarded in the SPL arena due to their overall design, relating to the motor strength, suspension Q, coil and gap design, and their surface area. The good news is that companies like RE, Adire, ID, etc. are reliable with their information and don't post an X-max specification just for the "ooh" factor of it, their subwoofers are capable of moving a lot of air and retain excellent control of the subwoofer at the same time. It's all about matching what you want with what you need to do it with.