Blackmagic Decklink audio problems

I've got two macs exhibiting identical problems. The decklink card will not play out audio unless FCP is running and in the foreground. For example, I can play a song in itunes and I hear nothing. If I cmd-tab to FCP, then I can hear the song. The same goes for all applications except for FCP (Safari, Soundtrack Pro, DVD player, etc).

Settings are correct in System Prefs: all audio plays out of Decklink Audio.

I am currently using driver 6.6.2 for the decklink, but I downgraded to 6.1 and nothing changed. (And then upgraded back)

Mac Pro 2 x 2.66
4GB RAM
Decklink Pro HD (Dual Link)
OS X 10.4.11
FCP 6.0.2

All updates current except QT 7.3.1

These are new builds with the Decklink cards, so the audio problem has always existed in these two Mac Pros.

Anybody out there run into a similar problem?