non powered sub recommendation

Please offer your opinion on a non powered sub to mate with Magnepan 1.6 or 3.6. I already have amp and Velodyne SMS1 to do all the hookup stuff.
Hi, Check out- TBI They have two sizes, Magellin VI or Magellin VIII depending on the size of your room.
I use VMPS subs with my Apogee panels...I like them.