The Sonus Faber would like power, especially if you play loud. Most Class A amps are small 30 W or less. I had a Schitt. Sounded good but not enough grunt. You need an amp with some weight, a big transformer, etc.
There are several AB amps that would sound quite nice. Parasound, Anthem, etc. Look on here or other places you will be set.
PS. I personally will always own a class A amp but high efficiency speakers make it easier.