Most people don't understand how a digital recording is an exact reproduction of the analog waveform with no distortion.  Nyquist-Shannon says if you sample an audio signal digitally at twice the maximum bandwidth, as defined by the low-pass filter, mathematically the only signal that come out the other end, after going through another low-pass filter is the exact sine wave that went into the recorder. So, the digital sampling, actually can reproduce the exact analog sine wave -- all thanks to math. A Russian scientist invented Nyquist-Shannon in 1933 but it was rediscovered by Nyquist and Shannon in America circa 1964.