I have a micro USB charger for my Bluettoth headset (Plantronics) and another for my work phone (LG). I can't seem to get the X to charge up using either??? Interestingly, if I take the iPhone charger and change the cable from the USB/30 pin to the USB/micro USB it works fine. All the chargers are rated 5V. The X on any regular USB port on any computer I've tried so far. So, if the 5V is the same for all those chargers, is then just a question of driving enough amps into the X?