This issue applies to Mac Pro ONLY. Boot into Windows (via Boot Camp), plug your speakers (if they aren't already) into the line-out jack in the back of the Mac (do I get points for that alliteration?). No sound, period, no matter how you try to configure the sound options. I've had it with this, I really have. And Apple keeps dodging responsibility, blaming Windows. It is NOT A WINDOWS ISSUE. The Boot Camp drivers are at fault for not recognizing the line-out jack in the back of the Mac Pro. I've resorted to plugging my speakers into the headphone jack on the front, that way I get sound in both Mac OS and Windows. But it's an ugly solution. I want Apple to take responsibility for this and fix it. Or if anyone has a fix, I'd greatly appreciate it!