JC1, Pass X250.5, CJ Premier 350, Krell 300cx

Impossible to answer without the partnering speakers. Amps by themselves do not sound like anything.

How low in impedance and sensitivity? What is the frequency response, impedance curve and phase angle look like in the speakers, among many other factors? Size, shape and composition of room, type of music preferred.

What about the front end? Preamp, source components. All are needed to understand how best to answer this question. We listen to systems, not amplifiers.

Stevecham:

I respectfully disagree with your unhelpful remarks. Amps do have a very distinct sonic character. I was not asking about total system synergy, just about the specific attributes of the amps themselves. With that information I can better decide which amp will fit with the rest of my components and have the synergy I desired. I do agree synergy is very important (matching impedence etc), but amps do have their own sonic signature, which Agoners can comment on. I am interested in comparing and contrasting these amps. If you have compared amp X vs amp Y in system C,D,E,F , then compared amp X vs amp Z in system C,D,E,F you should be able to tell me the results of amps X vs Y vs Z. So yes, remaining components are not necessary to answer this question. Thanks

You won't go wrong with the JC-1s. In high bias, they are gut crushing yet subtly musical monsters.

Pass over the JC1 and Krell for sure, but I can't speak to the CJ 350, can't talk about what ya ain't heard.

loon