It is also possible that the amp itself could have one channel wired out of phase with the other. With balanced equipment this is very easy to do by mistake!
I would reverse the speaker connections on one channel only just to see what happens. Does the center image improve? Is there less information sitting in the speakers and more spread out between them? If so, then we will know that there is indeed a phase problem, and the next step will be to find out where it is.
I would reverse the speaker connections on one channel only just to see what happens. Does the center image improve? Is there less information sitting in the speakers and more spread out between them? If so, then we will know that there is indeed a phase problem, and the next step will be to find out where it is.