If you are using the included AC Adaptor to power the
unit and you have a (regular) 6-pin firewire cable to your
desktop or rackmount computer. You need to UNPLUG
the AC Adaptor, the M-Audio Firewire1814 and Firewire410 device does not need it!
If you have a 6-Pin FW Cable don't use the AC Adaptor.

The AC adaptor is mainly for Laptops, many of which use
4-Pin (mini) firewire ports. 4-Pin ports typically are not
able to supply power.