Help set up active crossover

[audiobomber]

I'm trying to mate a pair of BESL S5-MTM monitors with a pair of Rocket subs, using a Marchand XM44. In theory, I should be fine with a second-order HP and a 4th-order Linkwitz-Riley low pass at 80 Hz, because the response of the BESL shows the usual acoustic suspension 12dB/octave slope at the bottom of its range.

But when I measure the MTM's in my room, they don't fall off at 12dB per octave below resonance, in fact they don't drop off at all, and have quite a hump at room resonance (30 Hz). The Rocket subs OTOH fall off at 6dB/octave above about 70 Hz. I get plenty of bass without the subs, but trying to use the monitors alone is not working for me because they sound stressed when run full range. I've tried numerous combinations of 80 Hz filters, including:
12 dB HP, 24 dB LP
12 dB HP, 18 dB LP
24 dB HP, 18 dB LP
I have 24 dB HP, 24 dB LP, but I haven't tried that one yet.

The reason I'm not happy so far is that the response is lumpy in the crossover region and some combinations result in dips at the crossover point (not corrected by phase). I've tried reverse phase and even 45 and 90 degree phase. . None of the filter combos produce much of a null in reverse phase. Is there a correct answer to this, or just keep trying to arrive at whatever sounds best?

S5 MTM SPL curve: http://www.bamberglab.com/s5mtm_spl.pdf
UFW-10 SPL curve: http://www.audioholics.com/reviews/s...searchterm=ufw

In my listening room, the subs behave much like their curve shows, except for a big hump at room resonance, which I control using the built-in single point EQ set for 30 Hz, 0.5 octave, -12 dB gain. As I said above, the MTM,s don't behave at all like the SPL curve shows, they're not rolling off at all at the bottom.

[audiobomber]

I think I have this sorted out. I'm using the 12dB/octave high pass and the 18dB/octave low pass, and I fine tuned the EQ on the room mode, and everything is sounding great. My bout with audiophiloia nervosa is over for now.