Question about Delock Stabil

Ok, I've got it... it's not the device that makes noises (buzzing noises) but the power supply unit that comes with it.

Of course, when I press the buttons, I hear that. The computer also makes device searches when a USB device reconnects (if this is set). But otherwise the HUB is pleasantly STILL!

Neither is mine.

I don't think so. I have never heard of mine.