>>How does one 12 inch driver cause this much havoc ?
I think there are two major things :
1. The 600 has a pretty big box and lots of port area. That has to help with the bass output around the tune point (20-ish Hz).
2. Lots of good subs will put out roughly the bass output of the 600, but you can't run them full out because they sound bad when they hit their limits -- but typically you hit the limit at one specific frequency WAY before you hit the limit at the rest of the interesting frequencies.
The 600 just backs off a bit if you hit a section with exactly the wrong frequency and volume, which lets you run happily at a higher volume than most subs will allow and enjoy the greater bass output at the rest of the frequencies.
Something like that, anyways. I guess the 600 watt amplifier doesn't hurt either
