No longer in production but the last version of the Entech LF 20 was quite impressive. Two 10" long throw woofers, each with its own amp built in. The active crossover built into the subs allowed several frequencies and bass boost if desired. I am using stacked LF 20's (two LF 20's on each channel) with Crosby Quads and they mate seamlessly. In my room, they are plus 3 db at 26 hz. As an aside, their external passive crossover was terrible but easily replaced with two Teflon caps and a TKD pot.
