Bandphan, hence my suggestion for crossing them over at 40Hz. As with all Deftechs whatever the webiste says the frequency range is say 24 Hz-30kHz, always double the lowest range and that would be the proper crossover point so the speakers sound it's best.
My 7001's rated 18Hz-30kHz, doubled it's 32Hz (about the point where bass drops like a rock, so i cross over at 40Hz)
Studio Monitors rated 24Hz-30kHz, doubled should be crossed over at 50Hz I cross em at 60Hz.
CLR2002 32Hz-30kHz, doubled is 64Hz, I cross em at 60Hz
Mythos gems rated at 60Hz-20kHz the gems -6db point is at 137kHz so I cross em over at 120Hz (and that's pushing it, i should cross over at 150Hz)
Even though the towers come with built in subs, they really should be considered great mid bass drivers instead, use an outboard sub for real deep bass.