I ended up trying apulse myself last evening and it seems to work fine, so crisis averted for now. I don't particularly enjoy having stuff much with LD_PRELOAD and friends but I suppose it's less effort.

Thing is... I know what you're saying, and I don't doubt it's probably just some trivial issue that I can solve with a two-hour trip to Google and my PA config files. However, not running PA works fine, and has been working fine for like 12 years on every computer I've owned. It's literally no effort at all. I could spend some time getting sound to work again, or do absolutely nothing at all and have it working fine, just as it's worked for the last six years on the machine in question.

The days of endlessly troubleshooting ALSA settings and OSS wrappers aren't really gone if we're troubleshooting PA settings and ALSA wrappers instead.