Other than a very slight "click/thump" when powering on, my Studio is dead silent. This may be obvious, but I would try disconnecting everything except headphones, doing a factory reset, and powering it on. If the noise goes away, I'd try reconnecting things one by one. Let us know if you determine it is bad hardware. I love the performance and features of this unit, but my worry when getting it was that a company with limited experience with this kind of a product doesn't have the necessary experience to make a robust product like RME. Would like to keep an eye on other people's experiences.