I've owned a few of Sonus Faber speakers such as the Elipsa, Guarneri Homage, Cremona A monitors and (Cremona Elipsa Auditors in a HT environment as surrounds) and I don't remember any of the SF being a tough load for any of the amps. Not very familiar with the newer SF products but the generations prior have always sounded great with SS or tubes to my ears. I personally had great success with McIntosh, Bryston, BAT, Lamm, ARC from what I can remember.
