Curious:
Low frequency extends only to 30 hz whereas the DIs, with twin 10 inch drivers, go down to 20hz. Wonder why there isn't greater range with the 15" drivers; could it be the cabinet size?
Tekton Polycell15
103db made with a different array which is more like a horn or waveguide. 15" dual woofers. He has it as a pro audio product. Seems ideal for flea-watt home use as well.
http://www.tektondesign.com/tekton-pro-audio.html