Hello, I have the same issue even if my OP-1 doesn’t charge via USB. Would a stereo DI box help? Something like this? https://dbxpro.com/en/products/djdi
if i remember correctly when i researched this
the ground loop noise doesn’t have anything to do w/ charging
(which is why the turning off charging option doesn’t help either)
it has to do w/ the usb midi and audio sharing grounds and the way USB is designed
personally, a DI box didn’t help me in my situation, the lil ground loop isolator totally did.
but maybe yours is different. only one way to find out
in theory that is correct. in practice there seems to be a difference in noise when the OP1 is charging from the USB bus and when it’s not. my setup here is fairly sensitive to ground loops but of the whining bus noise type - and turning off charging removes the noise I otherwise experience. an ymmv thing…