Hi Bob. Without knowing it, you are actually arguing my response that you quoted. That there was no way, no how the customer had such a horrible experience when he first turned that DAC on. That is why I put zero, let me repeat, zero weight on that word. With some rare exceptions, today's DAC *devices* are built on DAC *integrated circuits* that are so good that you really can't screw them up that way. And their spec sheet mentions no word whatsoever about the need for burn-in.
I don't know who John hired to design that DAC, or who is manufacturing them. But I am confident even in the worst case, they would not put out a product with such aberrant performance when first turned on. Since the customer said after just one hour performance improved, we know it was not broken which would be the only explanation for such poor performance as he reported and John kindly provided word for word.
You ask for common sense explanation but you can't use such here without understanding how DACs are designed and how "impossible" it is to get them to convert digital samples to analog with such performance when first turned on at customer site. One needs to use engineering common sense and everything there would point to impossibility of the device being so non-performant, however you want to interpret the wording.
And I trust you that you have as have others. No disagreement on that. The issue is working backward, without technical knowledge and that of psychoacoustics, and coming up with a technical explanation of cause and effect. Study of the former would say what I explained above. Study of the latter would tell you the elasticity of our hearing system. We don't hear the same over time. You can listen to a piece of music 100 times and at episode 101 hear a note you did not. That note was always there. Your brain simply did not focus on it to hear it. This should make common sense to you.
You are pleading with me to understand your universe as you know it. How about doing the reverse a bit and try to understand the universe on the other side? That there are readily explainable causes for differences we hear that are not attributable to causes we attach them to. So to the extent you hope for me to bend your way, I hope you are not so obstinate as to refuse to do the same in reverse.
I will address your last point in the next post. Thanks for chiming in.