I just published a small library to do pcm wave output on two digital pins. It uses SparkIntervalTimer (which you manually need to import into the project too since dependencies don’t work yet).
Also you need to convert a (short) sound file into a c-header and add it to the project.
I added a wiring diagram on github now. And there is also a sample wave_data.h included. Now I need to figure how to update my library on build.particle.io.