The functionality and operation of the Fantom-X and your computer-based application(s) will be the same no matter which type of connection you are using - the only difference is how the MIDI signals are routed.

This is useful it you already have a MIDI or Audio/MIDI interface connected to your system, or if there is not a USB driver available for your computer. This will use the MIDI In and MIDI Out ports on the back panel of the Fantom-X, which will connect to the interface, and the interface will then connect to a standard USB port on your computer. This will use a standard USB cable connected to the square 'USB COMPUTER' port on the back of the Fantom-X and then to a standard USB port on your computer. There are two ways to make this connection. The Fantom-X series can be connected to a computer so they can be integrated with music software applications as well as the Roland editor applications. Fantom-X Series USB Driver v1.20 for Mac OS 10.5 and Earlier. Fantom-X6/X7/X8/XR Driver Version 1.0.0 for OS X 10.8.

Roland fantom x driver