I am not an audiophile. I have heard many times that hardware X has good/bad DAC. The "has" signifies that DAC is a kind of separate chip inside it.
As far as I know, DAC is an algorithm to fill in the blank from digital number samples to voltage output. Isn't this achievable by any computers today? Can we change the quality of DAC just by rewriting the algorithm?
For example, "iPod Touch's DAC is not bad". Is it possible for Apple to issue an update that will improve the algorithm to make better analog signal from digital numbers?