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

@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

@Audiotroy--never thought the room was that big, but you may be entirely right. I assumed it might have something to do with the fact that there is a half-wall between the living room and the kitchen. Maybe I just need the subs based on the size of the room.

@jl35--that may be it too. I really didn't expect to need subs. Or at least I was hoping that if I spent that much money I wouldn't need them.