I am running N801s with FPB-650MCs. I would not use another amp. The FPB amps match very well with Nautilus speakers.
If you end up going with N801s, you must realize AND accept that they need power to make them right. My suggestion, should power not be where you want to spend you money, find another speaker. That said, the Krell amps work well, (FPB series, older are NOT the same) but so would Mccormack DNA-2 Deluxe. I had nice result from Audio Research tubed monos at normal to slightly above normal listening levels, but the N801/N802 like juice, need power to make them sing, and also decent levels of volume to get the most out of them.
Bottom line, keep the Krell if going Nautilus.
Dan
If you end up going with N801s, you must realize AND accept that they need power to make them right. My suggestion, should power not be where you want to spend you money, find another speaker. That said, the Krell amps work well, (FPB series, older are NOT the same) but so would Mccormack DNA-2 Deluxe. I had nice result from Audio Research tubed monos at normal to slightly above normal listening levels, but the N801/N802 like juice, need power to make them sing, and also decent levels of volume to get the most out of them.
Bottom line, keep the Krell if going Nautilus.
Dan