So, we seem to have two camps:
"Objectivists": If we don't have a scientific rationale for it, and can't meaure it in an objective manner, it doesn't exist.
"Subjectivists": We hear what we hear. If there is no rationale, and we can't measure it objectively, find a new rationale and refine the measurement.
Of the two, the subjectivist approach actually is closer to the true scientific method. The objectivist approach to measuring perceptual differences has long since taken a wrong turn, and is not attempting to address serious methodological flaws.
For example, in any given ABX test, what control groups are run to insure that the test is sensitive to differences in aspects of sound that are known to be detectable to the human ear. Without some objective index that a test is capable of detecting known differences, much less hypthetical ones, the test is useless from a scientific standpoint, much less a hobbyist one.
Any objective test has to take into account the nature of the process of perception. The assumption is usually made that perception goes one way. That is, a receptor is triggered, a response is sent to the brain, which we can either detect or not. If not, there is a tendency to invoke the magic word "placebo" and call it not real. However, this is only part of the story. The path from receptor to brain can be called "bottom-up" perceptual processing. However, there is another set of neural pathways going from the brain that actually modulate the input received by the brain. These pathways can be inhibitory, and can actually block an impulse triggered by a receptor from ever reaching the brain. This is "top-down" processing. It's one of the ways that the brain modulates input. The literature on this goes back many years.
So, we ask another set of questions. Under what conditions would a signal from a receptor be inhibited? Would it be inhibited in some people but not others? What would be the factors that would cause a stimulus to be perceptable or not? Some of these factors are psychological, and not physical. How does attention modulate perception? In a complex sonic environment, attention allows us to hear things of interest to us, and filter out others. Think of a crowded room, with multiple conversations going on, and then someone mentions your name in one of the conversations. You might not have been picking up anything from that conversation previously, but you will be now.
How about fatigue effects? For some perceptual stimuli, we habituate, and become less sensitive over time. For others, we sensitize, and become more sensitive. For still others, we are insensitive until a learning process occurs. Why are some systems fatiguing over the long haul (but sound great when we first hear them)? Will a DBT or ABX quantify this in any way?
Want to talk about whether cable differences are real or not? Then you need to understand all of these phenomena, and include many others that I can't fit into a short internet response, and include them in your testing scheme. Until then, all a so-called "objective" test can do is to tell you that you're not hearing a difference under a given set of conditions in a given time and place. Whether you would hear differences under other conditions, in other setups, with other experiences, simply cannot be generalized from the test.
The oversimplification of the word "placebo" doesn't work. As used by the objectivists, it's a catchall to describe any perceived effect that they can't explain. A question for them: "Is that really science?" Before using the word "placebo", it would be useful to understand exactly what's going on with it. In part, it could explain subjective impressions of non-existent differences ...or are they really non-existent? Remember, the brain can filter perception. It's equally likely that the brain can filter out real and measureable sonic differences as it is that it is causing people to hear things that are not. In fact, the so-called "placebo effect" may be reflective of the brain's filtering of perceptual stimuli, to the point where perceived differences where none actually exist is occurring in the nervous system. While the stimuli may have been identical at the receptor level, differences in filtering could cause the differences in the stimuli to become very real by the time the impulse actually reaches the brain.
There are also certain replicable ways that perceptual systems routinely distort incoming signals (see any optical illusion for an example). These tend to be shortcuts, that allow us to perceive and react to stimuli without having to spend hours processing them. They also need to be accounted for in any model of how we perceive an acoustic stimuli.
If you're getting the idea that perception is a complex process, you're getting closer. Use of any test involving perceptual differences needs to take into account the nature of perception. I've long since learned that methods for "objectively" measuring perceptual stimuli really aren't.
I haven't even bothered with methodological issues, for the most part. Suppose that you go through the whole process, do the statistics, and find that the reported differences between pairs of cables is not significant with alpha set at 0.05 (conventional in science). What does this mean? At alpha= 0.05, there's still one chance in twenty that the reported absence of a difference is wrong. And there's still no indicator of just how probable it is that the reported absence of a difference is wrong. That's a second statistic, sometimes called beta. I've yet to see any ABX test report this, but I'm open to reading one.
True "scientific" study of why some people hear differences between cables is going to be a much more complicated process than simply whipping out the old ABX box. Until then, my idea of the hobby is that it's intended to maximize the enjoyment I get out of listening to music. For my purposes, if I hear it, it's real enough for me.
