Hey Dan,
Yup, STK WvOut, which WvOut2 is based on, seems to support 24+ bit audio, but ChucK hardcodes it to use 16-bit for WAV/AIF. Also the latest release of ChucK broke MAT-file output from WvOut(2).
It *should* be trivial to convert a MAT file to WAV in Matlab/Octave, but I can't get MAT files from ChucK (using an older version with functional MAT output) to open in Octave.
We can definitely add adjustable bit-depth to WvOut + fix MAT-file output for the next release. But until then I don't have a great answer for this.
spencer