The 896mk3 is the flagship for MOTU's unique "hybrid" audio interface line, which delivers universal FireWire and high-speed USB 2.0 connectivity.
MOTU audio interfaces can connect to any Firewire port. Just plug in and go, with any standard cable. The 896mk3 Hybrid provides two FireWire Type B ports, which provide the most reliable FireWire connection available. The ports operate at 400 Mbit/s, and they can be connected to any available FireWire port on your computer, either Type A or Type B. If your computer has FireWire Type B ports, use the included 9-pin-to-9-pin FireWire cable. If your computer has either standard Type A ports or miniature Type A ports, use the appropriate 9-pin-to-6-pin or 9-pin-to-4-pin FireWire cable (sold separately).
FireWire has long been recognized as a reliable, high-performance connectivity standard for professional audio interfaces like the 896mk3. Meanwhile, high-speed USB 2.0 has also developed into a widely adopted standard for connecting peripheral devices to personal computers.
To fully support both formats, the 896mk3 hybrid audio interface is equipped with FireWire jacks and a high-speed USB 2.0 (480 Mbit/sec) connector, and you can use either port to connect the 896mk3 to your computer. This gives you maximum flexibility and compatibility with today’s ever-expanding universe of Mac and Windows computers.
If your computer does not have a FireWire port, then obviously you will need to connect the 896mk3 to one of its high-speed USB 2.0 ports.
If your computer has both FireWire and USB2, then it is your choice, and your decision will depend mostly on other peripherals you may also have.