Hey again! We've gone quite far with the project, enough to load a sample of an actual sound into the software, but we're a bit confused with the audio quality.
We're getting this horrendous sound out our DAC. We've resisted and capactized the output, but still to the same effect. Different headphones, same effect.
Starting Sample Sound: http://freewavesamples.com/1980s-casio-violin-c5
Result from Speakers: https://instaud.io/XOM (Sorry for the weird site, I'm not sure where else to upload it)
We're using a simple TRRS breakout with Tip, Ring 1 and Sleeve soldered to wires that connect to DAC0, DAC1, and Ground respectively. Something interesting to note is that disconnecting ground doesn't do much.
If you'd like to view it, the code is up on github: https://github.com/Beeper-Weepers/Vuision/blob/master/instrument_main/waveform.h
The software isn't the exact same as the one used to create the sound, though, I modified it a bit to continuously play the sample through it's list size. Not much different other than that.
Image of wiring setup: http://imgur.com/a/r1UeF
Thanks for your help!