You don't mention price. If your bedget for a sub is at or below $4500, then you might consider Aerial Acoustic's SW12 12 inch sub. If your budget is around $2k or less, then you might want to look at the Bag End Infra-sub or the Triad Platinum 18 inch subs.
The Bag End and Triad retail at $1600 and $2000 but you may find them used at just over half price. Both are quite musical.
The Bag End and Triad retail at $1600 and $2000 but you may find them used at just over half price. Both are quite musical.