I never fully realized you could mix two digital PCM by simply alternating their samples in the output to the DAC. That's fascinating. I realize now that some music output on the single bit Apple II computer may have been approaching mixing in the same way...
OctaMED anyone?
Interesting, an Amiga tracker used the same technique? I've always been fascinated with this topic - in the past I simply summed and divided.
I can't say for sure as I didn't see the source code, but it definitely felt that way, back in the day. Compared to "regular" tracker, OctaMED always sounded more digital, more aliased, more bit-crushed, which I presume was an audio artifact of sending A/B samples to DAC.
... which is, by the way, the same audio quality I would describe PPG's sound with.