@james633 , I think you underestimate yourself. Building one of these kits is not that hard. Finishing them nicely with something like Piano Lacquer is not so easy but you can have that done by a pro for reasonable money. I tell people otherwise just to cover the enclosure with black carpet.
The JTR woofers are very interesting. It looks like they are using a Dayton reference 18" driver which is excellent. Plywood construction is better than MDF. They are using a smaller sealed enclosure, a lot of power and DSP to force the woofer down lower. It is still a very large subwoofer. It would be impossible for me to fit four of them into the situation I have and with multiple subs a woofer that large is overkill. But using two in a point source system in a room 15 X 25' or larger would be fine if someone did not mind the look. You will also have to weight that enclosure down to keep it from shaking. I would put a granite slab on top of it. Used with digital bass management I would think it would be significantly superior to any Rel, SVS or JL sub. Here is the driver https://www.parts-express.com/Dayton-Audio-RSS460HO-4-18-Reference-HO-Subwoofer-4-ohm-295-472
The JTR woofers are very interesting. It looks like they are using a Dayton reference 18" driver which is excellent. Plywood construction is better than MDF. They are using a smaller sealed enclosure, a lot of power and DSP to force the woofer down lower. It is still a very large subwoofer. It would be impossible for me to fit four of them into the situation I have and with multiple subs a woofer that large is overkill. But using two in a point source system in a room 15 X 25' or larger would be fine if someone did not mind the look. You will also have to weight that enclosure down to keep it from shaking. I would put a granite slab on top of it. Used with digital bass management I would think it would be significantly superior to any Rel, SVS or JL sub. Here is the driver https://www.parts-express.com/Dayton-Audio-RSS460HO-4-18-Reference-HO-Subwoofer-4-ohm-295-472