Best Subwoofer To Use With A Two Way Speaker System


I received my new Wilson-Benesch Vertex stand mounted loudspeakers in mid-January.  After about a 200 hour break-in period and a few position tweaks I am now in audio nirvana but without the final low octave or so.  I carefully chose my associated electronics and couldn't be more pleased.  My Sutherland N1 preamplifier has 2 outputs so I can use it to drive a crossover/subwoofer system.  
I am entirely certain that my spouse would never stand for me to add a W-B Torus Infrasonic Generator & the accompanying Torus Amplifier at about $12,000. I would like some assistance from those that have the experience to advise me of something very good to mate with my system at a much more reasonable cost.  Thanks



128x128perazzi28
"gdnrbob" 
You absolutely did and I apologize for the oversight.  You get first creds!
Thank you
Post removed 
perazzi28, thank you for your informative response and the accompanying links, very helpful.
I would respectfully suggest the Goldenears Supersub XXL..  I love mine and have had them successfully mix with a few friends' various speakers that lacked low end. Each of them ended up buying at least one and still are very happy with them. The enclosures are reasonably sized, attractive to look at and have lots of servo processing to allow easy placement.  I find them very musical and easy to integrate. 
"aaronm"
Thanks for the recommendation. I will take a look at everything suggested. It truly helps when knowledgeable people have valuable input.