Excellent choicer, @conlad! More important that where a sub woofer (or any component, for that matter) is manufactured (or assembled), is who designed it. Brian Ding of Rythmik is a very smart guy (PhD in physics, I believe) and subwoofer designer, and his subs really good. Sealed, Ported, Open Baffle. 8", 12", 15", 18" woofers, all with his own servo-feedback system. Even better than the servo woofers in the Infinity RS-1b I owned for a few years.
The Rythmik woofers themselves are manufactured by TC Sounds, by the guy (I have forgotten his name) who designed and made the legendary LMS woofer ALL the monster sub DIY’ers were using when that $1,000 driver was aviailable. Very high quality woofers.
Jim Salk likes the Rythmik subs so much he offers them built in to some of his speaker models. Jim also builds really nice enclosures into which he installs the DIY kit version of the 12" and 15" Rythmiks, those enclosures having the most incredible bracing I’ve ever seen. It looks like the honeycomb pattern seen in beehives! Beautiful real wood veneers too.