I have owned the Extremas and powered them with a Rowland Concentra. The sound is warm and for low to medium listening levels can be very satisfying. I also paired them with a Classe 25 (250 watts) and the sound opened up considerably. Tube gear in my opinion would be a poor choice considering that the Extremas can take all the power you can throw at them and still ask for more. I agree with Tacs as I am using an Llano VPLEX-200 with Artemis EOS monitors and the sound is superb. I would look at a minimum of 250 watts of Class A power, more if you can afford it, in order to appreciate what the Extremas can do.
Plinius SA-100 vs. Rowland Model 2
anyone able to describe the differences between these amps from personal experience - they will be used to power Sonus Faber Extremas - I am looking for more transparency and dont listen at high volumes (the Extremas seem to be susceptible to treble glare), and clean (not fat) bass