Subs for SF Amati

@w123ale   REL have always been and remain sub-bass speakers. They begin a steep roll off in the 40Hz neighborhood with the T9X dramatically -6dB @ 27Hz. 

Your Amati's are rated at (I'm assuming -3dB) @ 28Hz providing almost twice the output energy at that frequency than the T9X. Unfortunately, speakers typical middle of the room placement is often in the rooms null, choking their low frequency. This would be my serious consideration contemplating a speaker with even lower frequency response. Example: Many demonstrations of statement speakers are accompanied by satellite boundary positioned subwoofers.

Like a beyond human hearing extended frequency tweeter, a -3dB subwoofer can provide far more subsonic at their rated output which enhances the low frequency presentation I think your looking for. A REaL subwoofer.

The caveat is their single or dual room positions can be critical to their performance. I've had excellent success using the Crawl test to map the rooms potential bass mode areas taking the trial and error guess work out of the subs room locations for now and with any future subwoofer. 

Many users add DSpeaker or MiniDSP to an affordable basic subs and report great improvements by adding flexibility and integration control. Good luck with it.          

What about the Sonus faber line of sub woofers?

https://www.sonusfaber.com/collezioni/#gravis-collection

Thank you all for very helpful input. SF Gravis is an interesting thought, although I wonder if a company like REL that focus 100% on subs would have better performance. I know there are different perspectives, but I’m definitely in the camp of using subs in 2-channel. For my system it has significantly increased the sound stage and the weight and depth.

It’s interesting that there a lot of high end speaker options but not many subs.