It depends what you are hooking the USB pass
through up to. The Prodigy runs around 5v at 1 amp. The passthrough out of a standard USB port on your computer runs at a steady 5v at .5 amp. If you use the USB port on a wall adapter, a portable powerpack or a cigarette lighter adapter, chances are you are getting 5v at 1 amp. Personally, I notice a difference between 5v at 1 amp versus 5v at .5 amp.