I recently brought a USB flash type mp3 player, and I find when listening to it on good hps I can hear a constant whirring in the background, and definite whirrs and buzzes when I’m searching through content. It’s not audible on low quality buds but it gets annoying. Why can I hear the memory?
It’s call RFI, and it’s caused by the radio emissions from the digital part of the circuit being picked up by the analog part. It’s hard to eliminate completely, but good designs (ipods) do a better job than cheap ones.