The Classe makes a lot more current and you may not get the best it has to offer if your not making it work a little harder for it.
The valves on the other hand might feel more at home playing 12-15 ohm high efficiency speakers at low volume and would probably sound great doing it.
Those same speakers on the Classe will play much much louder with relative ease and you still may not be reaching its sweet spot where it begins showing its real talents.
What kind of tube amplifier do you have? And what types of music do you listen to in order from most to least?