Tube amplifier to power Sonus Faber speakers?

I would like to suggest ARC as a tube amp to consider. FWIW, I believe ARC is currently using SF as its reference speakers when checking the performance of its gear.

That should be no surprise since SF and ARC are member companies of the Fine Sounds Group. This may be a leap of faith on my part, but that might permit an inference that ARC and SF make for a good match.

The specific ARC amp you might want to consider is the Ref 75. This pup has garnered quite a bit of favorable comments. I own its big brother, the Ref 150. The two amps share similar circuitry and probably share a similar house sound.

Not sure how much you want to spend, but the ARC Ref 75 is a keeper.

Thanks for your clarifications Al. Let me add one too.

Most ARC amps use negative feedback and have "low'ish" output impedances, especially off the nominally denoted 4 ohm taps. Al .. as we have discussed many times before, this means that ARC amps with low'ish output impedances perform somewhat like SS amps -- i.e., like voltage Paradigm amps.

As I recall, the ARC Ref 75 has a robust power supply (520 joules) and low'ish output impedance off the 4 ohm taps (1 ohm off the 8 ohm taps; probably less than that off the 4 ohm taps). Ergo, it might not be a bad amp to consider.

That said, if the SF speakers in question (a) present very low impedance plots and highly negative capacitive phase angles in the bass spectrum, and (b) are not very sensitive, then a safer bet might be a high current SS amp with lots of watts. Or, a bigger ARC tube amp such as the Ref 150.

(P.S. J Atkinson measured the Ref 75's output impedance off the 4 ohm taps to be .75 ohms at 20 Hz and 1K Hz. See: http://www.stereophile.com/content/audio-research-reference-75-power-amplifier-measurements)