Originally Posted by nick_charles
Better is a loaded term, but here is my take on it.
The job that a DAC has to do is to accurately reconstruct a continuous waveform (changing voltage) from discrete samples. If a DAC can do that with negligible added noise/distortion and with no added phase difference between channels (perceived as wider soundstage) it is a good DAC whether it costs $50 or $25,000 - if it cannot do that it is flawed. It it adds it's own character to the sound it is flawed, if it rolls off before 20K it is flawed, basically if it is not razor flat from 20 - 20K it is flawed, IMHO of course. If two DACs are very different, to the point of audibility then at least one of them is faulty, IMO.
Of course rigorous testing of audible differences is rarely performed here, mostly we have (IMO) unhelpful, poorly controlled sighted tests which are open to all forms of cognitive bias.
The biggest single difference you will ever find betwen two "good" (i.e flat) DACs is volume pure and simple, the line outs on different DACs can vary by several db , my own Entech is a good 0.7db hotter than my Marantz, this is a difference easily detectable and often mistaken as greater dynamics and so on.
Once you adjust for level many times the differences between good DACs become very very hard to detect.
As for audibility of other differences between good DACs, well normally unless you are talking about NOS jobbies then distortion/noise are so low as to be undetectable in normal listening, jitter has never been sufficiently proven by any rigorous testing to be an audible issue, so you can forget that.
What is left ?