Booming bass from my B&W Nautilus

Are the speakers spiked ?.You do probley have to move them away from the back and side walls, if this fails .Buy horns and a SET amp .just kidding.I havent had good luck with BMW .

Check the settings on the 380s. Are you using the Factory Supplied Spikes, to isolate them from the floor? Even 2 to 2 1/2 feet should be enough room from any wall for your N803's.

Other than those 3 things, I'm at a loss?

Yes the Sound Anchor stands are a wonderful addition, yet you have to correct the BOOM by placement w/ the Factory Spikes First! Sound Anchors are not, an instant Band Aid cure, until after you've found your speakers sweet spot.

I agree with much of the above. However, I've never been a big fan of B&W's partly for this very reason.

1. Try placing the speakers further out into the listening area. Unless the room itself is to blame, this should help.

2. Use 3 Star Sound Audio Points mounted under each speaker.

3. Try another speaker cable. With many cables, there is a certain amount of time smear. This can make the bass sound somewhat ill-defined in the lower regions. The Audience Au24 speaker cables will really clean this up in my experience.

4. You do not mention what your components are sitting on. The rack and/or stands can also make a serious impact toward a more appropriately defined bass (as well as the rest of the spectrum).

If the above does not improve your situation, then it's either the room, speakers, or perhaps the amp.

-IMO

If this is indeed caused by room interaction (most likely) you could try to narrow down the frequencies that are resonating. I have found the Stereophile Test CD or Test CD 2 useful for this purpose. These disks have test tones set a specific frequencies, allowing me to narrow down a resonance problem and immediately tell if a change in speaker placement has helped. It is quite obvious when you listen to the different test tones which one is causing the problem.

In my room with my current speaker placement I get a problem with the 40Hz tone. When I play music that has energy in this area, this part of the bass response is emphasized way out of proportion to the point that it is nearly unbearable to listen to some songs.