Nice link Maty! I would really love to venture into that sort of DIY would it not be that components here are very hard to come by. I grew up watching my father do boards like that, and really love the feeling of having something you did with your own hands.
Maybe at some point. Right now, I just bought another RPi3 to link to the uDSD and see how that turns out.
Edit: According to the nuPrime graph, there is equal amount of odd order harmonics than even order harmonics, is that correct?