Don't buy it. Crap. Absolute crap. Mine interfered with my firewire hard drives. (It almost sounded like workclock problems but would eventually bog down to a hault when playing samples off the FW drive.) I ended up having to buy a separate pci card to take the stress off the firewire bus. Still, it's not working well. 9 crashes today and I'm in the middle of a contract. You're way better off getting something by RME. My other machine has a hammerfall card in it and it is so much more reliable. RME also has software that allows you to route what's going in and out of your card. Profire (not so pro) doesn't have any routing software so if you're planning on plugging in something like a few gigastudio machines or in my case, a second and third mac running kontakt, you're left with a very confusing routing solution. Long story short, I'm taking my PFLB back and have already bit the bullet and splurged for an apogee symphony/16x rig. Something I really should have done in the first place. That'll teach me for trying to save a buck and take the cheap route... Maybe someone else has something positive to say. Maybe my system is posessed but that's my experience with the box.