I was looking for a dual USB AC adapter to the bedroom to be able to charge two iPhones. Since iPhones are right on the bedside table, of course, is also the charger in direct proximity to the bed. Generally, the power supply has done his job, only 1 point has meant that I have returned the device: The charger whistles unbearably loud. First was the whistle only heard when no device has been loaded. A quick test showed that during charging the pipes disappears. Ok I thought, I can live with. The first night was then that the pipes but also appears during charging. I am even woke up several times, so I felt annoying whistling. After 2 nights uncomfortable I decided that charger to send back. For my case, that's useless. In addition, the blue LED lighting is so severe that it interferes in the bedroom. For this, I would, however, found a solution.