Sealed Subwoofer Recommendation

I am looking for a good sealed subwoofer that'll integrate well with my Dynaudio Evidence Temptation speakers. I have a tremendously large room that suck out bottom 1/2 octave of bass from my speakers and I don't feel like upgrading to Master model and pay five figure more to obtain the bottom 1/2 octave. I've tried Velodyne DD15 and it worked somewhat but found it to be too slow and loose sounding. Up for consideration is JL Audio Fathom F113 that Absolute Sound and Home Theater praised but one of my friends say that this is one of those King Kong subs that is not very articulate and he recommends Focal SW 1000 Be. Anybody heard this? Has anyone heard Zu's Method which is dual 15 inch paper cone sealed subwoofers? How about Martin Logan Descent or VMPS very large array? Or Dynaudio Sub 500?
If you have a large room...go with a pair of subs. Place them near the mains and the blend will be seamless. While I have never played around with the Velodyne DD15...most agree that it's a pretty darn good sub.

The fact that you could not get it to blend properly for only the bottom octave (20hz-40hz) hints at one of two did not set it up properly, or...your room is so large that you need two subs.

I use a pair of VMPS subs with my Apogee Duetta Signatures...With a lot of trial, the blend is seamless in my fairly large room.

JL Audio is about your only choice that comes to mind. Also, if you can find one.. a REL Storm V. Seems like Sumiko doesn't want to sell a good sealed box sub.
There is nothing loose or slow sounding about a DD-15. It's possible that the sub was exciting room modes to a greater extent than the Temptations and thus seemed to loose and slow.

Do you have any bass traps? What are the dimensions of your room?
DD 15 doesn't work then try this one: