NHT Classic Fours bi amped

Is anyone running these speakers, and if so, can you get away without a sub if you run a separate amp for the woofers? They claim you can, but I have never heard them this way. I'm skeptical whether on not they can actually do a subs job. If they eliminate the need for a separate sub, then I'm interested.
I have classic 4's biamped using an old HK reciever for a tubey top end and 2 channels from the NHT Power5 for some bottom power and I do not miss a sub at all. Im using the x2 crossover as bass management and it all works great.
i don't feel the need for a sub either, but note i only have a 2 channel stereo/ht system

surprisingly good speakers for the money btw
Im running Classic Fours bi-amped w/Power5 and Monarchy Audio SM70-Pro 2x25wpc class A amp. Heavenly sound for music and plenty of low end for ht. A great combo! If you decide to get a sub make sure it can go well below 27hz or so (27 hz being the bottom end of the NHTs).