Crossover confusion

Hi All, 
  While I'm not a technical expert with stereo electronics and software, I do understand a lot of it. My problem is clipping on my woofers when playing the Stereophile test CD track 31 (20Hz 1/3 octave at -20db ). 
It would probably be best that I list my equipment from source to sound.
1.) Cambridge CXC transport
2.) Nad M51 DAC ( via fiber optic)
3.) Audio Research LS3B preamp ( all other interconnects are Kimber PBJ's ) 
4.) Bryston 10B Hi Lo crossover. ( Settings are 80 Hz for the low pass. 70 Hz for the high pass. High pass db is 0.)
5.) Low pass frequencies go to a pair of Audio Fathom F-113's which are active subwoofers
6.) Hi pass frequencies go to a Krell FPB 300 power amp
7.) Kimber T12 cables connect to PNB B741 speakers ( with two additional midranges) that have been fitted into a 
    pair of Dunlavy SC-IV's. The cables are Bi-wire that are common at the amp. The smaller conductors feed the midranges and tweeter. The larger conductors feed the woofers.
  My thoughts are that none of this 20Hz signal should  even be going to the Krell amp.  While I haven't heard any clipping when listening to music I am concerned. I was researching passive crossovers and came across Marchand Electronic's website. They make both active and passive crossover's. One of the diagrams show a hybrid setup that uses an active crossover with the hi pass going directly to the midranges and tweeter and the lo pass going to a passive crossover and then to the woofer. Before talking to Marchand Electronics I thought it would be a good idea to come here first since I've gotten a lot or good info here. If I have to use a hybrid setup, it would also be useful to know what the crossover Hz should be. The PNB B741 woofers bottom out at 25 Hz. Hope this is enough info for those that can help.
  Thanks to all concerned