Best amp for Sonus Faber

Many SFs are fairly efficient but have a low impedance dip usually in the 200 hz range. An amp that can drive low impedance loads is usually a good choice.  

If you’re after tonal richness, dynamic range, exquisite midrange and outstanding transparency, consider Accuphase E-4000 or E-5000. I own E-650, one of the best decisions I’ve made in my 20+ years of audiophile journey. 

Congrats on your new speakers, they are gorgeous! 

This depends on what specific improvements you’re looking for and what sound characteristics are most important to you.  Also, what’s your budget and are you looking for new or used?

@stephenwerner 

Sonus Fabre are considered a warmer speaker so I’ll bet a top neutral amp would pair well. The Boulder 866 is exceptional. Good luck in your search ! 

I've always liked the Luxman/Sonus Faber combo. Your 509Z is actually the first one that comes to mind since in my opinion it is a little more punchy or full bodied than some of the others. Especially the tube designs. As someone said above I think you might have a hard time beating what you already have.