Thank you for your patience
My apologies for the delay as I have been rather busy.
I usually approach a recommendation by theorizing the best possible solution regardless of cost (monetary or otherwise). Then, I scale it back by the constraints dictated by the customer. And, this time is no different. I will start by pointing out our biggest issues. First, this is a two-way and a sub, not a three-way. We are dealing with a midbass and a sub, not a midrange and woofer. It is hard to separate the lower mid from the midbass. Especially in a room that large. The sub would sound best 45 down, but the 805 is not palpable below 60 in that big of a room. I do not like kimber anything on that speaker, but I'm not crazy about your low-pass selection either. The high-pass is ~ok. I also assume you have your amp biased to your liking.
We are limited on space inside the cabinet, and short on budget to move the XO external. Have you ever considered moving the amps close to the speakers making the ICs long, and the speaker cable shorter? Have you ever tried a high-pass filter on your main amps? I do not know what the input impedance is for those monos, but a quality film cap (0.15uF for say a 22k input imp) on the input would help. Or, potentially altering the pre output for the monos.
The binding post and internal wire could stand to be upgraded... For some reason, I was thinking the low-pass inductor was cored (btw, you have your networks marked backward in your original post)...
With your budget I would:
-Ditch the low-pass board, and remotely mount the following: http://www.soniccraft.com/product_info.php/pair-alpha-core-12-awg-190mh-p-5034
We would dewind them to 1.45mH. You would use a new prototype cap for the 6.8uF ($66.84 ea), and a http://www.soniccraft.com/product_info.php/56-ohm-mills-mra-12-p-660
Point to point wired with http://www.soniccraft.com/product_info.php/jupiter-cda-101-16-awg-p-5003
Twisted pair where possible.
-Same series prototype caps ($51.24/$85.80 ea) "shoehorned" (larger/heavier) onto the high-pass board. Replace the resistor with http://www.soniccraft.com/product_info.php/33-ohm-mills-mra-10-p-3645
This will have you in for ~$540 plus shipping, and leave some budget for a pair of nice small caps, longer ICs, and new low-pass speaker cable. Select to taste after you put a couple of hundred hours on the combo above.