BB Accessories :: Max Charger Amps For Outlet To Micro Usb?

i do not have an electrical engineering background and in fact know very little about amps, watts, etc. however to understand my power and charging needs for the playbook, i googled. anyone who knows this better feel to correct me.-the included outlet to micro-usb charger provides 1.8amps at 5volts.-the typical pc to micro-usb cable provides around 0.5amps at 5volts.-the typical power usage of a playbook while active and running is 2-3 watts (which is about 0.5amps to 0.75amps at around 4 volts (depending on battery state).So if the above is true, the pc to micro-usb charger will pretty much cover the usage amps or maybe even less but wont actually increase the amount of stored energy (breaks even).The included charger will provide about 1amp of juice to store after subtracting the 0.5 to 0.75amps of usage.but what is the maximum charger amps or voltage which can charge the playbook the fastest via outlet to micro-usb?is 5v the maximum and amps are the limiting factor? or can any amount of voltage and amps be used? i need it to be microusb not the magnetic post cable because my stand uses microusb. the reason i mention usage while active instead of standby mode is because i plan to run a night table clockapp which will draw 2watts but still want to charge the device quickly.