My Sonus Faber Amatis have weak bass even though I'm running ML 536s--800 w/ch into 4 ohms

OP,

I think we are zeroing in on the problem. You are looking for crazy high bass.

B&W are know to be very bass heavy. And you you owned B&W803’s and did not think they had enough bass. So, what is going on here sounds like you want a very bass heavy system. If you want accuracy down to the bass and then a big kick, you are going to have to use subwoofers. and adjust them for the kick you are missing. Amati’s are made to sound natural and accurate down to around 28 hz or so and they sound that way,

I got rid of my subwoofers when I got my Amati Traditional. Don’t miss them at all, plenty of bass, Note, Sonus Faber makes three levels of subwoofers. That Gravitas are absolutely beautiful and match the Amati.

Alternatively you could go with the current top of the line B&W 800 speakers and massive MacIntosh monoblocks. These really rock and are very bass heavy. On the other hand MacIntosh is details / high frequency light... so the might create a problem for you.

@torke 

I love great fast tight bass so I can empathize. There is a nonzero likelihood that your speakers work perfectly as designed, but they're just not right for you.

My humble suggestion would be to audition Revel Salon 2 and see if you are pleased by their sound.

Nothing else in your audio chain has the potential to cause a massive bass deficiency, so I think comparative speaker listening is the fastest way out of this predicament.

Happy listening is around the corner. Good luck and keep us posted!

the OP does say that the speakers sound "great" and with subs "comes alive" .... maybe all is well, except he didn't expect to "need" subs ...

I have a similar sized room. If you have ruled out wiring problems you may want to return the speakers. It wouldn't be the first time something Italian left the factory with a problem. 

I am running Yamaha NS-5000's driven by Wyred 4 Sound SX-1000R monoblocks with a Rythmik G25HP subwoofer. Bass is fine on axis. 

You may want a full surround system from what you write. Get three bids from sound installers. Big rooms are trickier. 

well why is this unexpected, bass response is directly proportional to a speakers output, vs room volume, and his space is gigantic, when you combine all three rooms contiguous volumes, so of course you need subs.

Dave and Troy

Audio Intellect NJ