Okay, this isn't quite the same problem I thought it was at first glance, and probably isn't the same problem described in this thread to begin with. It turns out that I actually do have proper sound in-game, but for some reason, it's just very, very quiet. The game's volume meter is set near maximum, and winecfg's sound test plays at a normal volume, but in order to hear the game sound properly I have to turn the physical speaker volume dial up far above what anything else has ever required. Sorry for the noise. I'm still bewildered as to why this happens in the first place, and I'm not 100% convinced there isn't an issue needing attention in the mix somewhere, but at least I have a functional solution.
