So I sat down to record some tracks and immediately was hit with this super irritating sound that I've never noticed before and I can't for the life of me work out what it is. - It's constant, like a helicopter or an idling engine (mp3 attached), and is the same whether I am touching metal components or not. It never varies in pitch or intensity. - It is directional in that some angles lessen or increase it, but it occurs whether I plug into my Focusrite Scarlett into my laptop or into a Zoom H4N on batteries elsewhere in the house. - I tried through my amp and it was very audible out the speakers. - I have tried several different cables and turned various devices in my studio on or off. - Holding the cable in certain positions can make it worse. At first I thought it was a problem with the preamp in my active jazz bass, but I can detect the exact same sound at the same frequency when I use my Stingray so unless they have both gone wrong in the same way at the same time it must be something external, right? I can't hear it when I switch my jazz to passive mode.