If your JC-1s aren't yet broken in, I suggest you haven't heard them. Play music through them around the clock. Volume level doesn't matter (just not zero), nor does high or low bias setting. They will become much more agile, dynamic, sweet, and extended. I recommend giving them the time they need, as deals on other amps will come along if you decide to change.
Others have expressed the .5 versions of the Pass amps are better, although I have not heard them side by side. The X600 is not an involving sounding amplifier, in my opinion.
It may be worth noting that performance measured by Stereophile (Feb. 2003 issue) of the JC-1 showed output far in excess of ratings, I think nearly 600 watts into 8 ohms before clipping and about 1100 watts into 4 ohms.
Others have expressed the .5 versions of the Pass amps are better, although I have not heard them side by side. The X600 is not an involving sounding amplifier, in my opinion.
It may be worth noting that performance measured by Stereophile (Feb. 2003 issue) of the JC-1 showed output far in excess of ratings, I think nearly 600 watts into 8 ohms before clipping and about 1100 watts into 4 ohms.