The Klipschorns did everything (and I mean EVERYTHING) right except for the bottom octave.

So I'm trying to think of the shortest point from A to B, by which I mean lowest cost within acceptability parameters. Unfortunately, I was unimpressed even by pricey REL subwoofers, and once we're talking 3 grand anyway, then we're talking replacing the whole speaker system, not augmenting existing stuff.

So my dilemma is this: can I build or otherwise come across a subwoofer with the horn loading characteristics I like (dynamic, super low distortion) w/o tipping the equation into the "shuck it all and buy a new set of speakers" side.

Two (or three) options being: Pi, HSU style subwoofer, or one of these spiral horn jobs.

Once the cost gets above about a grand, then it makes more sense to sell the Khorns and buy Pi's. Of course, I will have a spare grand laying around when pigs fly.