From what I can tell, it looks as if the Akai LPK25 doesn\'t have a Midi port, but only has a usb device connection. You\'re right in thinking the digispark wont be able to act as a usb host to commune with this keyboard. You might be able to get some sort of usb host shield later, but I haven\'t seen anything like that announced yet. Your best bet here would be either an Arduino with a USB Host shield, or the potentially cheaper Raspberry Pi which has USB host ports built in.