Congratulations, you have identified a new species of wwise Vorbis. The vorb header is shorter, packet headers have no granule, and most importantly, there seems to have been some change in the stream format itself. I have a few guesses, but this is a fairly drastic change. They've always stuck with the standard Vorbis datastream format, but now it looks like they've decided to attack the bloat there. I'll let you know how it goes.