(semirelated): The Amiga, all the way back to the Amiga 1000 from 1985, had 4 channel (2 on the left, 2 on the right, no configuration here), 8-bit DMA output with a 6-bit analog amplifier.

I've heard claims that the 6-bit analog amplifier was sufficiently precise that you could combine two 8-bit channels into one 14-bit channel (in 1985!) per stereo channel. I guess it's possible, but I still question this. Anyone here know if that's actually true?