Which is imo a strange reaction to oivavoi´s post.
Maybe it would help to read something about qualitative methods and why it is often used in scientific work; sometimes a combination of quantitative and qualitative methods gains really astonishing results.....
You need to decide if you are interested in whether a report of difference accords with objective reality, or in the phenomenology ('subjective reality') of audio perception.
Regardless of what 'qualitative' methods may show, a single device is not two devices; a phantom switch experience (e.g. like what Amir reported, where he *thought* he had made a difference, but realized later that he had not) is not an experience of an *objective* difference.