That would be really cool. Never got around to trying it, but I'm really curious about the subjective quality on the 12bit A/D conversion looping back to PWM D/A.
-The 12 bit A/D provides a (theoretical) 72dB of S/N, so if you can do that at a decent sample rate to get sufficient bandwidth, the digitizing should be good.
As long as the PWM D/A has a good clock to keep the PWM ratio accurate, I think it should be eminently listenable, given a proper reconstruction filter and a decent power supply.
Check this out -- really good discussion of bits and SNR: https://www.xiph.org/video/vid2.shtml jump to the 11:00 mark to find out just how many 'equivalent bits' those old cassette 'mix tapes' of yours had...
As long as the PWM D/A has a good clock to keep the PWM ratio accurate, I think it should be eminently listenable, given a proper reconstruction filter and a decent power supply.
It would be fun to try this.