I had a Velodyne CHT8 which I used with a pair of M3Tis. The CHT8 is only good for about 30-35Hz, but it's quick and very musical - a perfect match for a pair of M3s or M2s. I also have a CHT10 which I use in a dual sub set up with an SVS 20-39. The CHT10 is an excellent sub. If you can find one used in good condition in your local Penny Saver or Classifieds, I'd save myself a bundle and go that way.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.