"I don't 100% get the band limited signal bit. How does band limiting imply that there's only a single possible reconstruction of the digital signal?" The band

"I don't 100% get the band limited signal bit. How does band limiting imply that there's only a single possible reconstruction of the digital signal?" The band limiting here means removing frequencies above the Nyquist limit. This allows for a unique solution. In the case these higher frequencies aren't removed, you get aliasing. One solution is the real one, and another solution folds back into the lower frequencies causing distortion. You are probably already familiar with aliasing in the visual domain. This is the effect that causes tires to look like they are rotating backwards once they reach a fast enough forward spin. "Isn't there also an argument that frequencies above 19khz can be heard by some people so need to be accurately represented?" See http://people.xiph.org/~xiphmont/demo/neil-young.html http://people.xiph.org/~xiphmont/demo/neil-young.html for some details on this. "Would be interesting to see a complex analogue signal being fed through the digital pipeline and then inverted against the original to see the differences." The square wave is fairly complex and included in the video. While he doesn't invert the signal, he does show it fed through multiple times and then compensated for the delay.