You can use a 2x4 HD from miniDSP. You can route the full frequency range to your amp, and then only do 80 yards and below with a low pass filter to correct your subs. If you're concerned about that unit affecting the quality of your audio, you could also put it in line between the subs and the main with the right accessories
I guess the Anthem AVM-60 can't do this?
Wondering if I should try integrating my Hsu VTF-3 Mk5 w/ the Thiel CS 5i's when I set them up in a few weeks or so (most likely w/ an XPA-DR2). The 5i's reach a bit lower than John's 3.6s, but the low bass is also what will tax the amp the most as it reaches down near 1 ohm and may benefit from some help, especially for the occasional rock music I might throw on.
And if that Hsu sub mates very well w/ the 5i's, maybe I'll consider buying a 2nd matching sub to be used for both music and movies...
_Man_