Just some feedback after playing with PropBoard audio today. Wow! Sounds great and plays loud! And nice API too.
Not easy to look at waveforms and measure distortion etc. from a class-D amplifier (due to PWM modulated output), but certainly sounds OK to me.
Discovered by accident that it is not a good idea to connect the - (negative) terminal from the speaker output to GND (or oscilloscope ground clip…), but luckily I did not break anything. My mistake, and obvious if you read the specs for the amplifier chip, but maybe it could be mentioned in the “Connecting the speaker” chapter in the Propboard manual.