Q: No audio for Mac Pro (mid-2012) running Win8.1 on Boot Camp

I've seen discussions around the 'net centered around this difficulty for Macbook users, but users experiencing this with a full-size (desktop) Mac Pro are hard to find. My mid-2012 Mac Pro, (running Yosemite on the Mac side) recently got entangled in the world of Boot Camp when I recently installed Windows 8.1, and I have since been unable to produce audio output from the Line Out. (My headphone output works fine, though it feels like browser audio seems a bit subdued. That's a topic for another discussion, though.) Most of the forum solutions for Macbooks that I've seen involve updating audio drivers, but I can't find any links or recommendations relevant to a mid-2012 Mac Pro. Has anybody else suffered this problem, and managed to conquer? I really don't want to get caught up in ping-pong between Apple's support geeks and Microsoft's nerds.