Ground loop b/w amp and phono stage

I recently bought the Ayon Triton integrated and when it is connected to my phono stage, Pass Labs XP-15, there is a major buzz coming through the speakers which increases as you turn up the volume. You can even hear it through the music when played at high volume. Needless to say, I'm not playing vinyl at the moment. But when I used the CD player, there is no buzz at all. It's only there on the input which the phono is connected to.

I have used cheater plugs, cheap cables with the ground removed, I've connected the amp directly into the wall plug, I switched from unbalanced to balanced interconnects, and am currently out of ideas. The Pass worked perfectly with my previous solid state mcintosh gear.