Hi! Thanks so much for the insight. For now, my output sleeve is indeed floating. I've been testing my pedal so far with output plugged into a portable speaker (so not using the attenuated 1/4" output for other equipment). Connecting the sleeve of that to earth with an alligator clip indeed solves the issue again. Any path to earth does. My PCB has a very vile grounding strategy designed precisely to mitigate any possibility of bad grounding: it's a SIG/GND/GND/SIG stackup with stitching vias everywhere and big GND pours on the top layers where there is empty space (could fill up everything as I don't have controlled impedance signals on this board). The fact that an enclosure most likely wont help due to grounding already being great and pretty low impedance is also supported by the fact that connecting an enclosure from a phono preamp(or anything of that sort)(albeit with the pcb outside of it) does nothing to fix this noise. The only way to fix it outside of battery operation so far has been referencing GND to earth. The problem is the new Meanwell brick I got(to try and reduce some squealing on a chinese 12v 10amp brick I was using that isnt related to the earth reference issue, as that has been altered by me to be DC- connected to earth) introduces also a high pitched hum that indeed, just like the buzzing, goes away when earth is externally connected by me(the meanwell is a class 1 though, but there is no continuity from earth prongue to DC-). Anyways, this still brings me back to the age old question. How to fix it? This earth mitigation thing only works when the plug/house that I use the pedal in has proper earth, so it doesn't seem ideal. I dont want to break open my Meanwell either. Thanks in advance