Amp/xover for Hartley 24 subwoofer

Hi Guys. I'm running a wall-mounted Hartley 24" woofer as a subwoofer to my Maggie 20.1's. It is powered at present by a Manley 170 watt mono tube amp, crossed over at 18db/octave at 50Hz by a Dahlquist DQ-10 crossover. My Maggies are rolled off at 6db/octave at 100Hz by a simple capacitor. I'm thinking I can do better with a solid state amp and a parametric equalizer/crossover at 24db/octave (keeping the 6db/octave for the high pass). Any ideas?
Marchand maybe?
The Audio Control "Richter scale" is what you want. 24 dB slope for both the subwoofer and Maggies will keep them inphase with each other at X/O. Also, the steeper slope will do a better job of keeping the Maggie diaphrams from flopping around trying to do LF.
I used in the past a Richter scale in conjunction with 3 ten's per side driven by a Krell Ksa150. I ran the mains full range and used the Richter scale to eq and blend the bottom end into the natural roll off of my now retired Dunlavy SC4's...Tom