Originally Posted by MorbidToaster
You'd have to get a sub the same way people with electrostatic speakers do.
You get a smaller, faster sub that can keep up. Unfortunately this means overall extension hurts.
The other issue with this plan is the fact that honestly the higher end stats go deeper than any sub that will keep up with them.
The "smaller faster sub" is a myth. When people suggest this, it usually means the larger sub was improperly designed, underamped, or "sloppy" due to faulty construction/design.
A 15" driver can't play a 25 Hz note "slower" than a 12" driver. A 25 Hz note is a wave that oscillates at the rate of 25 cycles per second. If the the 15" driver is oscillating at a "slower" rate, say 23 times per second, it's reproducing a different note. If the 12" driver is oscillating "faster" than 25 Hz, it's also playing a different note.
Any of the competently designed larger subs out there will be as "fast" as a smaller sub, and you don't have to sacrifice extension to get there. You do have to make a wallet sacrifice though...
For the OP - it's really difficult to get the synchronization of the phones and the subs nailed. I tried this a while ago with my JL F113s and quickly gave up on it. Then bought LCD-3's to get the bass I was looking for. Of course, it doesn't have the tactile feel of a sub, but it also doesn't disturb the rest of the house.