Amirm first sample was done properly, how would anyone have known that if the usb cable is connected it screws up!
That’s on Cambridge. Not amirm.
He shouldn’t have to apologise for anything.
I think we can all chill a bit about apologies and such, I agree with that he retested, gave the opportunity to show that it's a competent unit, and gave the precision on what has changed and why. Amir have put the extra work, no apologies needed there. But still we could debate about if "It's on Cambridge":
"Issue was brought up that this is an
instrumentation thing that the Audio Precision analyzer is creating a loop and ground noise that would not be there.
While this is true, I explained that I have tested hundreds of DACs that don't have this problem."
So the key word here is: instrumentation issue.
If a measurment shows a problem that don't exist in real life usage, we can hammer as much as we want that others don't have this "problem", but if it's only present when you connect an AP and in no other situation, if the matter is understood, and it can be demonstrated that no possibility it creeps into the audio signal when listening to music, well, it's a non issue, it's not "On Cambridge". Electronic designers need to use instrumentation of course, but they don't design to fix analysers weird behaviours. If some do, it may be by chance, it may be just different way of working the grounding scheme, or maybe they put the extra work on looking good on AP, but looking good on an AP analyser is not a design goal in itself, it's a consequence. If there is no problem, there is no problem.