By the way, there is no problem having the rcas and xlr's connected at the same time.
Have you tried disconnecting the XLR pair while keeping the RCA pair connected? I am aware they each have their own sonic signature. On my present preamp, having both connected at the same time skews the right/left balance and reduces the gain. This goes away when one or the other is disconnected. I didn't learn this until I tried it. Unless you've tried it, you also won't know if it affects your system's sound.
I'll consider trying a reversal a set of the AZ's.
Foster_9 (Threads | Answers)
So I am clear, I am not suggesting another set of AZ ICs. I'm suggesting unplugging the set you own and reversing the interconnects so the ends that were connected to the source are now connected to the Blue Circle, and vice versa.
Since the only new element in your system is the Blue Circle, I'd suggest the problem likely lies there. Perhaps try lifting the ground on the power cord that you use on the Blue Circle (by using a cheater plug).