A block diagram of a complete computerized audio-to-digital and back to audio again conversion system. If the two low-pass filters are matched and have infinite attenuation beyond one-half of the sample rate, the waveforms at points A and B are exactly alike! Since the waveform at point A is not audibly different from the input, this is truly a high-fidelity system. The computer could also be programmed to supply its own stream of numbers to the DAC, and it therefore follows that the computer can produce any sound.