Can I charge A300 with another kind of USB cable or via a wall outlet?
A300 can be charged through a computer with a standard USB cable.
When charging through a wall outlet, use a USB power adapter (not included in the product set). If you use an AC adapter, make sure that the adapter is marked with "output 5Vdc" and that it provides a minimum of 500mA. Only use an adequately safety approved AC adapter (marked with "LPS", "Limited Power Supply" or "UL listed").