Gordon Holt, editor of Stereophile, wrote a brilliant analysis on the strange gadgets of Peter Belt. It goes a long way towards explaining why these things "work". Some excerpts:
Psychological tests in other areas of human perception—vision, touch, taste, smell—have proven how unreliable they are, and how much they can be influenced by expectation or suggestion. There's no reason to believe aural perception is the sole exception to this. ...
For self-styled golden ears to be claiming, and trying, to be "objective" is to deny reality, because perception is not like instrumentation. Everything we perceive is filtered through a judgmental process which embodies all of our previous related experiences, and the resulting judgment is as much beyond conscious control as a preference for chocolate over vanilla. We cannot will ourselves to feel what we do not feel. Thus, when perceptions are so indistinct as to be wide open to interpretation, we will tend to perceive what we want to perceive or expect to perceive or have been told that we should perceive. ..
Despite heroic efforts to educate our population, the US (and, apparently, the UK) has been graduating scientific illiterates for more than 40 years. And where knowledge ends, superstition begins. Without any concepts of how scientific knowledge is gleaned from intuition, hypothesis, and meticulous investigation, or what it accepts today as truth, anything is possible. Without the anchor of science, we are free to drift from one idea to another, accepting or "keeping an open mind about" as many outrageous tenets as did the "superstitious natives" we used to scorn 50 years ago. (We still do, but it's unfashionable to admit it.) Many of our beliefs are based on nothing more than a very questionable personal conviction that, because something should be true, then it must be. (Traditional religion is the best example of this.) The notion that a belief should have at least some objective support is scorned as being "closed-minded," which has become a new epithet. In order to avoid that dread appellation, we are expected to pretend to be open to the possibility that today's flight of technofantasy may prove to be tomorrow's truth, no matter how unlikely...