XiphQT can't play Vorbis files at 96kHz
This Vorbis file plays in XiphQT 0.1.1, but it plays very, very slowly and unintelligibly. ogg123 won't play it at all, because libao is broken, but Cog and Audacity play it just fine.
The problem appears to be the sampling rate: When I open the file in Audacity, change the project's sample-rate to 44.1kHz and export as Vorbis again, the resulting file plays back perfectly.