Rear audio output missing via Adobe Flash Player (Pandora, Youtube borked!)

Title says it all. I’m finally settling into my new rig’s components and just noticed that I’m getting no audio on my rear speakers when playing stuff back via Flash Player.

“Ok, I just need to configure my speaker outputs.” Nope, that’s already done. 3D surround demo works. I get mirrored stereo from intelligent, useful applications like (gasp) Windows Media Player or Winamp.

Fucking Flash Player crap. There isn’t any configuration areas I can think to access where I might be able to tell it I’ve got more than just 2 speakers, and I don’t recall having any problems like this with my previous motherboard and Windows installation.

So I’m about to update the drivers on my ALC889A sound chip from 5.10.0.5449, if there are new ones available.

Can anyone think of anything else that might help me fix this? I need Pandora in stereo!

I’ve never been able to get rear speaker sound from iTune videos even with surround stereo expansion on.