I wanted to explore the possibilities with the PCM output. This tiny synth generates a sweet tone from three sine waves, coated in a thin shiny silver layer of aliasing. To spice it up, I also added a delay effect. You can play it with your keyboard. Use Z and X to switch octaves.
I do not plan to follow this route any further, because the possibilities are quite limited with the X16. I am sure one could do better than I did, but the X16 doesn't have enough power to provide a whole lot of flexibility in the sound generation (at least with PCM).
Find the source here: https://github.com/biermanncarl/cx16-tiny-pcmsynth
Feel free to reuse the code for your own projects!