I have my 3 week old C4's powered by a Rowland 112 amp and while I have thought about experimenting with tubes, I do also think these speakers will be at their best with big SS amps. I would like to try some JC-1 Halo mono's, as I think the Rowland may be a little underpowered to get the best out of the C4's bass.
I am also keen to hear what other longer term owners think.
BTW, I really love my C4's.