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.