And how would you output the result of that calculation? As an analogue waveform, perhaps?
So you have a “device” that takes a digital signal as input, and produces an analogue waveform as output. And it does so “perfectly”. All you need is a stylish anodized aluminum case for your device, and you can sell The Magnus for $$$$.
(One might object that The Magnus doesn’t have to do its computation in real-time (unlike a conventional DAC). But then you have to store your analogue waveform for later comparison. How would you like to do that storage? Perhaps as bumps on a vinyl disk?)