How nice to come across this thread! Sounds like you have quite a sub going for you there. I decided to take the PR plunge myself a month ago and am very glad I did. For some reason I always had a bias against the design but now know if done right it is a great SW option. I went with the exact same design as you with the 12” SDX and the dual 12” PR’s with the SPA1000. At this time I have been running it with a EP though due to a problem with the SPA which is being fixed by Bob. Anyway in my room I have a +-3dB going down to 14hz with no dsp. I couldn’t believe it, all that in a enclosure that size! It sort of felt like I wasn’t building a sub considering other builds I’ve done.. one being a 15” SDX LLT sono that I still have. Anyway I have this sub in my bedroom which is 25 X 12 with slanted tent like ceilings, so it comes in rather small at around 1000 cu ft. I’ve pushed the sub to 110dB peaks without correction and called it good. That works for me! Since I missed a couple small pilot holes on one of my PR’s it developed a little hissing noise and I took it as the PR’s were reaching there limit, but after investigating I found the problem and fixed it. If your sub is anything like mine the SQ is wonderful. Some of that is room dependent I admit and of course the +-, but none the same a stellar sub imo. I notice SVS has been brought up a few times in this thread, great subs to be sure (I have had 13 of them) but imo your dialed in with a superb sub in such a small package.
One thing I did do different is I elected to not to employ the amp as onboard. So I did gain a little enclosure volume doing so and I had to mod the baffle since I elected to go different dimensions than suggested lol. I didn’t account for magnet flare so I had to beef up the baffle mounting. I had the PR’s and driver countersunk, but now only the PR’s since the driver needed to be brought out a little so it would not hit the PR’s. Anyway I thought I would stop in and say Hi and let you know I really enjoyed reading your thread. Might you have any pics you might be comfortable in sharing?