What SS Int Amp to match with Sonus Faber?

I'd recommend the Jeff Rowland Concentra.

I have French-made Cairn's 4808A amplifier (about 2K USD new) and two monoblocks power amps K1 driving SF Cremona Auditors. SF speakers are so easy to drive that you do not need high-budget electronics to get the best out of them. Before I got the K1s, only the 4808A was enough to get crispy and musical sounds out of the SF. All depends on how large your room is.

Good listening.

Try both the Sonus Faber Musica and Pathos Classic II.

I have listened to properly set up Domus Concerto speakers using two different systems in the same audition room. One system utilized Hovland electronics, the other Naim. I, as well as other listeners, much preferred the Naim setup with this particular speaker.

I like the Concerto. It is a very well balanced and musical speaker. But, for my taste, it is a bit polite sounding -- not quite enough speed and oomph in the upperbass/midrange. That may account for the Naim sounding good with this speaker. The Naim has a much more propulsive sound. The Naim amplification was not an integrated amp, but their entry level separates. I strongly recommend that you look into Naim electronics.

I would also suggest looking for similarly dynamic and lively sounding electronics. It's just a pure guess, but I would think Ayre electronics would work well. I would also bet that Lavardin would sound pretty good too.