fundsgon
Audio Research Reference 150 and Sonus Faber Cremona
The SF Cremona need current, and a good amount of it if you want to hear the bass "at it’s best". This means solid state amps with big power supplies and bipolar (bjt) output transistors. (
I stipulated "at it’s best" because tube and mosfet amps will drive them and probably sound good, but they won’t get the very best out of them in the bass.
(I not sure if your Classe’s are mosfet or bi-polar) If bi-polar, you have the best amp already, look at other areas if you need to change the sound, source ect. Because the Classe are 50kohm input impedance you can even try passive preamps.
Sterophile quote:
However, that amplifier must still be capable of delivering a goodly amount of current. Even though the Sonus Faber’s impedance magnitude remains reasonably uniform at higher frequencies, it drops to 2.8 ohms through the upper bass, with a cruel combination of 4.5 ohms and a -53 degrees electrical phase angle evident at 73Hz (fig.1).http://www.stereophile.com/images/archivesart/CREmoFIG1.jpg
Cheers George