"Back stress" when operating with power supply interfere significantly: cursor jumps, trembles and flickers on the screen. The device can be operated without the alternative power supply (with a weaker charging current then but). After all, the design is good: by the ladder-shaped arrangement of the slots are also thick plugs side by side. Healthy working until the instrument TeckNet® USB 3.0 10 Port Hub with Power Adapter and USB 3.0 Cable, Black - Compatible with Windows XP / Vista / 7/8, Mac OS.