Yes, I saw that. I think that you're making a big mistake as I told you earlier you could get an INUKE DSP that would be waaaayyyyy better. Why would you go with a Def Tech as opposed to something else like a 1000 watt Dayton Plate amp which will have a much lower HPF? Parts express has a bunch of different plate amps that you can choose from. That Def Tech plate amp has a high HPF (I believe that 40Hz was the lowest that I saw on that) which will suck for HT applications. Plus it can only power one sub!!! If you get the INUKE it's a 2 channel amp so you'll have an extra channel left over. You'd have to buy two Def Tech subs which will cost you $500 (as per your price that you told me) while the INUKE costs $360.
Here's the INUKE 3000DSP for $360 shipped:http://www.zzounds.com/item--BEHNU3000DSP
Part Express plate amps:http://www.parts-express.com/cat/subwoofer-plate-amplifiers/332
I modeled your box which doesn't account for any bracing but it doesn't matter anyway as it's no good anyway. From what I gathered your box is 21.75"x22.5"x34.5" with a slot port of 34.5"(wide)x4.75"(high)x33.25"(length). Available volume after port and sub is 6.53 cubic feet which is more than enough room but your port isn't long enough.
Here's your box in red with 775 watts!!!
Lets just say that isn't good. If you keep that box size and go with a port that's 4"x10"x38" (17Hz port tune) and put 500 watts into it with a 16Hz 3rd order HPF you'll get what's in orange. Mine box with 775 watts in in pink.
The orange isn't bad as you gain a litle bit of low end but you're also loosing 3dB (half as loud) from 20Hz and up so the little bit of low end extension doesn't make up for the loss in decibals from 20Hz and up in my eyes. Also, there's not many dsp's or plate amps have a HPF that low. The MiniDSP can do it though. I'm telling you that a 4.52 cubic foot box tuned to 21Hz with ~775 watts is best for this sub as it has a flat frequency which the orange graph does not.