I've got a Bela that I would like to run using the built-in amplifier, so I'm using an AC adapter into the barrel socket.
When I run the patch from USB power (using headphones), it sounds great. When I plug in the AC adapter, I get a high pitched noise on all audio output, through the headphones and from the speaker output.
Is this just a problem with my power adapter? Or is there always going to be some kind of noise? Is there a recommended noise-free adapter I could use?