I'm trying to use Midi Fighter 3D in completely mobile setup with iPad.
Unfortunately iPad itself can't provide enough power for the device, so I'm thinking to give it power from mobile battery (usb hub + y-cable).

What is the specifics of power requirements?

On the back it says 5V 480 mA (milliampere). I tried 2 batteries with DC 5V 1A ~2000 mAh. They both don't start the device.