Ran into a problem in my studio (audio recording) earlier this month because of a powered USB hub with charging ports. I kept getting this faint rhythmic tickin

Ran into a problem in my studio (audio recording) earlier this month because of a powered USB hub with charging ports. I kept getting this faint rhythmic ticking noise in my guitars. I stripped down, and rewired everything in my studio to track it down. Not sure if it's the PSU, or something USB specific. But, as soon as I unplugged it from the surge protector, the noise vanished.