Hello everyone. I recently purchased a PreSonus Firebox. I have the main outs of the box plugged into a Mackie mixer hooked up to a QSC amp powering my studio monitors. Has anyone with a Firebox seemed to notice that the PreSonus Firebox is kind of noisy. I use to have a M-Audio 2496 PCI card and it was dead silent. Is this usual for firewire interfaces or is it just the PreSonus Firebox that is the culprit of the noise. It's sort of a high pitched wineing, modulating kind of hum. Not a 60 cycle hum. It's definitely originating from the firebox. Anyone else notice this?
Thanks in advance.

Music XPC computer
3.2 with 1 gig ram
PreSonus Firebox
Soanar
Mackie Mixer