WMD Performance Mixer & Metron Issue

Hiya folks, normally I'd just hit up the manufacturer for a question like this but they aren't taking inquiries until November according to their site so I'm hopin I can get some insight from you all.

If I crank the headphone out on the PM, the mixer is silent when not connected to any modules. If I connect any other module, there is a small bit of noise, but acceptable considering the output is being maxed out. If I connect the Metron to the PM, or any other module that is connected to the PM I get a ton of noise even with the output at 50%.

The noise is not hiss, it sounds a bit like an oscillator (maybe this is clock noise from the PM?).

Cases I've tried that have the issue: Intellijel 7U case with their TPS80W MAX supply and Doepfer A-100P6 with the PSU3.

Case I've tried that solved the issue: Custom case with two meanwell supplies that power separate rails. If I put the Metron and PM on different rails/supplies, I get no noise.

Unfortunately the custom case is huge and not portable and I'd like to be able to pack my case up for live situations.

Anyway, I'd appreciate any insight you all can provide.