So I have this old firewire power adapter that came with my 4g ipod with click wheel (no color screen), and i have a new ipod classic, can i use the old charger to safely charge my new ipod? I know it works cuz when i plug it in, it shows its charging, but the old firewire ones have a larger power output than the new usb small power adapters that have less output, so is it safe to use?