Donny, you are right, you cannot power the controller over the USB-MIDI cable. You would need a USB-host to USB-device cable connected to your computer or other device with a to-device USB port. However, the USB-MIDI cable is proper for controlling your 3k with the controller. It should work without any special effort on your part, as your 3k is probably set to receive in omni mode. If it does not work, you will have to figure out how to match the controller's transmit channel with the 3ki's receive channel. Good luck.