I dont want to write a phd thesis, what I have said shouldnt be difficult to follow yet.
So the most accurate method would be to include as many variables into analysis while isolating and retesting as appropriate to identification, and finally measure. When I say measure, it is just how we label our experience given a set of identical stimuli.
For example, words such as warm, clinical etc....
Ok, for the contraversial variables (for example, using a digital interconnect lead over short distances) can then be measured to personal preference, and so on.
I have found that most of the confusion arises when some people claim A makes a difference, while B disagrees, and what we have is an argument which has no clear solution. Alot of this is due to the differences in Personality: experience, ability to detect specific stimuli, attention to detail etc... I dont buy into the argument of superhuman difference, although there can be clear differences between any two people.
For those who do not agree, I think a repeated and statistically verified experiment can show otherwise.
There is much subtlety in sensation depending on biological differences, experiences, nature vs. nurture etc...
So far, we can try and explain the differences in opinion through these methods, otherwise what we get is one party claiming the other has had some sort of hallucination.
So, how does this apply to me the buyer. Stick with me........
Ok, it helps in:
Identifying variables that may have not been considered or been overlooked.
Providing a perceptual experience from which to decide priorities (remembering its a matter of taste combined with ability to recognise stimuli differences which can be tested- ie. not a hallucination).
[This is where the problems start........]
People begin their listening as a combination of this nature and nurture factors and have a conditioned response which varies with time.
So its not simply a matter of gaining analytic skills over time, but having been conditioned to your experiences.
Why, this is the very nature of music, its about taste which is accumulated over time.