As both are made by respected manufacturers that have been around for many years, one would think that the Rowland is more amp, as you do tend to get what you pay for in life and the Rowland is significantly more expensive than the c-j. What you should get for the extra money is, among other things, better parts quality and a better power supply, which typically (but not necessarily) translates into better sound quality.
As for quality of construction, my guess, based upon personal experience, is that the Rowland will have better build quality (Jeff's expensive gear always has incredible build quality), but again, maybe not.
If it matters to you, the Rowland amp, being designed around the ICe module, will burn significantly less electricity than the c-j.
In any event, at those price points, both amps are going to be excellent products. Despite the price differential, the c-j may prove to be the better sounding amp in your system, as it always comes down to system synergy. We have to assume, if you are putting such an expensive amp into your system, that the rest of your system is high quality as well, meaning that it will clearly allow you to hear even subtle differences among components -- this is all the more reason for you to demo the two amps in your own system to resolve the synergy issue (i.e., it would be foolish to make a purchase decision based upon what other people tell you about these components).
To say the obvious, make certain that you demo amps that are fully broken in (too many dealers do not bother to break in amps).
Finally, there are a number of other amps out there in the same approximate price range that will be competitive sonically (although perhaps not competitive from the perspective of build quality or reputation of the company for reliability -- a lot of the people making high-end gear are flaky and may not be there if your amp breaks).
Good luck.
As for quality of construction, my guess, based upon personal experience, is that the Rowland will have better build quality (Jeff's expensive gear always has incredible build quality), but again, maybe not.
If it matters to you, the Rowland amp, being designed around the ICe module, will burn significantly less electricity than the c-j.
In any event, at those price points, both amps are going to be excellent products. Despite the price differential, the c-j may prove to be the better sounding amp in your system, as it always comes down to system synergy. We have to assume, if you are putting such an expensive amp into your system, that the rest of your system is high quality as well, meaning that it will clearly allow you to hear even subtle differences among components -- this is all the more reason for you to demo the two amps in your own system to resolve the synergy issue (i.e., it would be foolish to make a purchase decision based upon what other people tell you about these components).
To say the obvious, make certain that you demo amps that are fully broken in (too many dealers do not bother to break in amps).
Finally, there are a number of other amps out there in the same approximate price range that will be competitive sonically (although perhaps not competitive from the perspective of build quality or reputation of the company for reliability -- a lot of the people making high-end gear are flaky and may not be there if your amp breaks).
Good luck.