If there is a difference in "sound", then the unit is either incompetent or defective. Tests and measurements will indicate whether there is a characteristic above the threshold of human hearing. If there are none, then there will be no differences in "sound".
You seem to be an apologist for subjective capabilities where such capabilities do not exist. You said ...
... yet you contradict yourself in the same paragraph by using "sound" as a legitimate basis for choice.
We all have a choice to make in life ... science or superstition. It would be best to choose wisely.
Jim