Sadly I'm pretty sure I've configured it exactly the way the manual suggests. I configured the H8000 for Throughput, I have connected only the H8000FW and nothing else via FireWire, and used analog connections to monitor the sound.

As the manual suggested, I've used the sound effects menu from the System Preferences. This works as an easy test for any audio interface. It does not get me any sound out of the H8000FW.