I am driving the C1's with a Jeff Rowland Concentra II, 150w into 8 ohms 250w into 4 ohms. This works fine but is probably the minimum I would find acceptable. I have also heard the C1's driven by Simaudio W7, this was not lacking for power either.
I have found the sound balance to be excellent at low levels with my set up, none of the hissy/tinkly sound you get with metal tweeters
I have found the sound balance to be excellent at low levels with my set up, none of the hissy/tinkly sound you get with metal tweeters