need help with subwoofer setup. crossover related

Hi all

I need some help with the crossover setup for my subwoofer. My neat mf5 speakers goes down to 29hz -3db while my subwoofer crossover is only to 40hz at the lowest. So i have a overlapping of frequency. 

My amp and preamp have no subwoofer management and my subwoofer do not have eq. My squbwoofer ia the genesis g928 with dual 12inch woofers.

My room is acoustically treated with bass traps and diffusers. I am very satisfied with my 2 channel and was trying to achieve to the low 20hz ffrequency for pipe organ music and to increase soundstage.

I know many will recommend getting a external dsp like mini dsp or velodyne sms1...but there will be an extra cable to connect these devices to my main system. And therefore will effect the performance of my main system indirectly. 
What i desire is just to crossover the subwoofer to 30hz lowpass to blend well with my speakers. Or to crossover my speakers high pass to 40hz to blend well with my subwoofwrs. 

So is there any way i can externally or internally crossover my sub to 30hz without affecting the main performance of my current speakers?

Or is there any way i can crossover my speakers to 40hz without an external device? (Without the involving another set orlf ultra expensive interconnects)
Thank you all for the help and sorry for the long post.