Ultimate sub?


So I have been in a slight upgrade stage recently. I just purchased a b&w HTM2 and I'm shopping for a sub. There is never much talk about subs it seems and so right now my two options are the Velodyne DDPlus 12 and the JL Audio Fathom 112. Are there any other manufacturers I should check out? This sub is an ultimate system purchase so I don't want to make a misstep.
dark_elation
BTW,

Rythmik also makes a vented (ported) version of the model. Here are some test results, if you're interested. Outside of group delay below 20hz, these are pretty impressive numbers. The subs go deep and loud and stay clean (for such low frequencies, anyway).

http://www.avsforum.com/t/1342986/rythmik-audio-fv15-hp-data-bass-test-results
If your willing to spend 12k or a tad less , the Ken Kreisel DXD12012 in a Quattro stack ( 4 subs 8 drivers in a push pull configuration with 10hz extenstion) in a pulsar configuration would be mind boggling and extremely musical, I have one DXD12012 and it will change your definition of what "true bass" sounds like! clean , clean, clean!