I'm kind of glad somebody brought up the DIY subwoofer community.
The tools, measurements and theory behind subwoofers have not only advanced, but also become readily available over the last 10-15 years. While on most days I am still smart enough to grasp my own limitations, I don't think it is ridiculous to assert that DIY'ers can construct subwoofers of professional quality. Available computer models are remarkably accurate, and - most importantly - the designer is only dealing with one driver and a very narrow, predictable, imprecise frequency response.
Subwoofers don't have to deal with baffle correction, crossovers, or - to a great extent - distortion.
I think this is a good reason why value-added technologies like Axiom's DSP are significant.
My contention is that subwoofer design is almost pure science (leading to commoditization and narrow margins), whereas loudspeaker design still requires quite a bit more art.
