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Whatever distortion introduced in a CDR after a digital to digital reproduction, it is not jitter. By definition, jitter is the noise introduced as a result of clock inaccuracies in the D to A or A to D process.
I suspect there might be some debate about whether noise can be introduced in a D to D copying process where there is no format conversion. I would contend there is no noise introduction by virtue of the copying process alone. It is true that the "bits is bits" school has had to re-evaluate the theory with respect to the introduction of jitter by a digital transport in what is ultimately D to A process (or, more accurately, D to D to A). But that is because a clock inaccuracy in the transport will translate directly to an inherent inaccuracy in the timing of the "bits" that the DAC receives, hence, more jitter.
When copying from D to D, assuming the same format, "bits is bits" still holds. Two CD disks have rigidly located physical "pits" wherein the data is stored. When a copy is made, the disks are essentially identical. Of course, alignment and sampling inaccuracies could result in occasional "drop-outs", but that is not jitter and does not sound like jitter. An isolated "drop-out" would porbably be completely inaudible, and a profusion of drop-outs would sound like a lot of crackle.
Having said all that, if you WERE somehow able to introduce jitter in the D to D copying process, then that which sounds like jitter in the CDR is no longer jitter - it is part of the coded sound on the CDR and won't be dealt with as real jitter would. In fact, a jitter reduction process as part of a D to A process would work to preserve that sound while preventing any new jitter as a result of the current D to A process.
No I don't. Remember that the upgrades you mention are upgrades which can positively affect playback in the *analog* domain or perhaps during the D to A process. But a D to D copy is simply not an audio event.
As a silly example, imagine you had a magnifying glass and a device which allowed you to burn a cd one bit at a time. You decide to copy a certain cd by reading one bit from the original and then burning that same bit on the new cd. Do you think that eating steak and eggs for breakfast (beefing up power)/eating breakfast slowly (regulating power)/eating egg beaters (filtering power) will affect the quality of the copy you are making?
@gboren +1 Thank you for a such a cogent response! With today's proliferation of expensive CD transports and the claim that some sound "better" than others your answer should give makers of such claims to pause!