Best subwoofer under $1,500 for Magnepan 3.6R

I know that this topic has been covered here in depth over the years and I've already gone back and read those threads in the archives some of which are quite old.

I'm looking to add a powered subwoofer to my Magnepan 3.6R speaker set up which is used primarily for playing 2-channel and 5.1-channel acoutsic Jazz and electric Rock (Rush, Pink Floyd etc...) I use a pair of Magnepan MG MC1 speakers for the surround channels and an Magnepan CC3 center channel speaker. My room size is 19 feet by 12 feet in size.

I've read great things about REL, Velodyne etc.. but most of those are too expensive for my budget. I'm looking for a subwoofer that will work well with my all Magnepan speaker set up under $1,500 new or used.

I appreciate any and all advice that anyone is willing to offer.