Best Subwoofer To Use With A Two Way Speaker System

My system is:
W-B Vertex Loud Speakers
EKSC Eagle 11' Mono Blocks
Sutherland N1 Preamplifier
Custom shielded interconnects
VPI HW 19 TT w/ Ortofon TA 110 Tonearm & Ortofon Cadenza Blue
   Phono Cartridge
Custom W7 Silent PC with an Delta M-Audio Audiophile 2496 sound card     running WinAmp for MP3's and other software for higher resolution  
    material.     
Kimber Bifocal X Loudspeaker Cables
Resolution/Imagining/etc. are nothing short of stunning.  Just missing the lowest octaves.
My room is on the smaller side however I have a very high ceiling and currently very little room interaction. I am willing to do some acoustic treatments and have some space to experiment with placement.

Perhaps check with W-B if there are any sub brands they recommend? Surely they realize not everyone who owns a pair of their speakers can afford a $12K sub. They may have some good advice and given the relative rarity of W-B in the marketplace might be a better source of advice. Also if you bought the speakers new how about the dealer?

Best Subwoofer To Use With A Two Way Speaker System

If you want to get HT type bass go with the multitude of 12"-15" units.

If you want one s/h that will blend perfect and give you an octave or two lower like it’s an extension of your Wilson-Benesch, then I suggest you look for an oldie but very nice Yamaha YST-160 or 305. These have proper linear amps twin 8" with servo control, very tight and musical, no doof doof droning HT sound from these. And they are the perfect height to use as stands, if you get two.

Cheers George

The days of putting a sub in the corner, choosing a bass heavy recording and trying to make adjustments while standing behind the sub are long gone. Today your matching the sub to your room and the mains. 

There are a few powered subwoofer brands that offer servo driver control and different forms of auto and/or manual digital signal processing built in. They can make integration unnoticeably seamless and lessen the need for room treatment. Some offer multiple EQ presets, visual setup monitoring from 200Hz on down, and remote control. You could even slave a lesser non DSP sub using the line level EQd signal and greatly lessen your rooms nodes while using smaller subs.

Do your homework by looking up the latest DSP setup instructions on the manufacturers sites that might suit your needs. They vary greatly as do the recordings ELF content, hence the remote control. 

I hope your spouse likes to boogie. Enjoy. 

https://www.audiogon.com/listings/subwoofers-velodyne-digital-drive-plus-10-inch-black-brand-new-sea...

I can't recommend more highly the B&W DB 1 sub that I've used for several years in a very high end system currently with Wilson speakers. You will never know it's in action except that your bass response will be awesome seemingly from only your main speakers. It also has great features such as room correction. They have recently updated these subs with remote control among other things. At $4500 list I can't imagine spending more and used ones when available(rare) fly out the door. Last thought. Get two if you want perfection plus they look good and are relatively compact.