Cannot address the CJ, but I owned an A21 and used it with my B&W 804s for a number of years.
I did end up getting JC1s and am glad I did. B&Ws need power (I'm sure you have heard that before), and the more the better. I don't think my A21 was as happy with the 3.5 ohm low end speaker impedance of the 804 (and other B&Ws) as the JC1 is. The JC1 can drive 2 ohm loads whereas the A21 is limited to 4 ohm loads.
Not that the A21 sounded strained or in difficulty. Its just that the JC1s sounded much better, so much so I would never go back to the A21.
If the CJ is tubed, I would think it would have more difficulty with the B&W unless listening levels are low.