I have tested mine with no firewire, not connected to a computer, powered up, with inputs in the front and it passed signal through to the direct outs on the back just fine. No computer involved. It was important to me to see that it worked liked that so I tested it with success. I also tested if it would pass signal through to the direct outs on the back when connected to a PC via firewire and everything is great and then the firewire wire is pulled, and the answer is no, it did not pass signal then. This all confirms what Presonus tech support predicted when I called to ask them what would happen in the above scenarios.