Amplifier Recommendation for B&W Nautilis 804

Go with a Plinius SA-100 used or if you can a Plinius SA-102, sound great with B&W's

agree -- plinius sa-102 or sa-250.

plinius + B & W = great match.

The Plinius is a nice choice. Still, even the older Used Threshold T200's are as good and stronger in the bass!...and overall strong enough at 100w even. The Pass X150 is also stellar. I'd chose these later over the Plinius in my experiences with 804's.
A possible better choice for you however is TO NOT SELL YOUR AMP YET! If you picked up another excellent bass amp(like most any of Parasounds offerings, which have adjustable gain controls), you could use that on the bottom, and yours on top, and BI-AMP! This is a MUCH STRONGER combination and option. Before you go "ditchville"
you might consider this. I would bi-amp those speakers, as it seems to be the way to go with them. I've bi-amped those speakers with dual Classe CA151's, and the sound was superb for the money!
Actually, it'll save you money, and possibly improve on bass if you end up with, say a Parasound HCA1500 or 2200 driving the bass. The one thing the Parasound's do well is bass indeed!
Hope this helps

I purchased the very same speaker, amp and preamp last year. IMHO the problem of lack of weight, particularly in the bass, is inherent in the speaker. Find yourself a REL Storm or comparable powered sub and your problem will be solved.

I also agree with wiggle --

If you like B & W Speakers, consider upgrading to
the N803's or N802's. In my opinion, there is a big
jump in quality from the 804's to the 803's, especially
in the depth and tightness of the bass, but also in the
overall coherency and sound-stage.

And, it *would* be interesting to bi-amp, using solid
state for the bottom end and tubes for mid-range up.

Like to hear the results of that experiment.

But first, I think I would upgrade the speaker before
the amp.

Check out the N803's before you try to solve the problem
with the amp!