Krell FPB 300cx enough to drive B&W Nautilus 801?

I'm about to purchase the Nautilus 801s, along with the Krell FPB 300cx amp. Would there be any significant improvement if I were to get the Krell 400cx instead? I emphasize the word significant, because price is a major issue. I know the 801s need power, so any opinions as to the sufficiency of the 300cx would be much appreciated. Thanks.
I have only knowledge of the 801N with the FPB650 monos. They are great.

Yes the power difference of an extra 100 watts would be only one dB, BUT..........

The 300Cx is based on the FPB200 and the 400Cx is based on the FPB300. There was/is a considerable quality of sound difference between the FPB200 and the FPB300.

Based on that fact, I would do everything I could to swing for the FPB400Cx.

By the way when I went to actively bi-amping my B&W800's, Dan D'Agostino strongly urged me to go for the FPB300, yet he made no urging for me to go to the 600.)
I have the 300cx driving the 802N. I would first put the extra money into biwiring and then go from there.
Have you ever try Pass Labs' Alpeh 2 ? Give it a trial, it won't dissapoint you. Arguably best SS !
Thank you all. Richard (Drrdiamond), I'm alittle confused (and very ignorant). Are you saying D'Agostino encouraged you to go for one stereo amp of 300 watts rather than biamp? Or can you biamp with 2 stereo amps? I thought only monoblocks were used in a biamp scenario. Thanks again.
I auditioned both the 300cx and 400cx in my home system before I bit the bullet and dug deeper to purchase the 400cx. I have Thiel CS6s. The 400cx made an immediate audible improvement in dynamic contrast, air and detail and bass extension and sped with these speakers, which require much current to drive properly. My wife confirmed (thank heaven for small miracles!) The only thing that prevented me from getting a 700cx was simple lack of $$$$$! But I not hesitate if I could swing it.