An often quoted (by naysayers) article on power cable ABX testing is here: Secrets of Home Theater and High Fidelity Power Cable ABX Test
There are couple of things about the test that give me pause for reflection:
1. A valid test, or any evaluative procedure, must evaluate a thing under the conditions it is most likely to be used. Blind trials are appropriate for some things and inappropriate for other things. Blind trials are appropriate for the evaluation of medicine when the medicine is administered under conditions in which a patient would take the medicine on their own in a non-supervised environment.
2. Every audio ABX test I have read in audio publications uses a setup that in no way reflects the way a consumer would listen to their audio system in their home.
Question 1: Why do some people cling to a fallacious, inappropriate test? This would seem to undermine their credibility.
I'm all for test and evaluation, provided the test is appropriate to the thing being tested.
This widely accepted ABX test was administered in a way that demonstrates an ignorance of the way stereo works. The picture below shows the participants for the ABX test referenced above:
Figure 1. Secrets of Home Theater and High Fidelity PC ABX Test Participants. Are any of these people
audiophiles? Is this the way they listen to music on their audio systems in their homes? Really?
Notice that the listeners are positioned in three rows with two to three persons per row. It is my understanding that the critical evaluation of a high fidelity stereophonic audio system must be done from the "sweet spot", i.e. the spot directly between the speakers where the stereo image is optimum. Unfortunately, for critical listening, only one person can occupy the sweet spot at a time.
The gentleman in the blue shirt appears to be in the sweet spot. However, we can reasonably deduce that his stereophonic perception was negatively impacted by the gentlemen on either side of him. One can only wonder how much imaging, detail, clarity and whatnot was lost due to sound reflecting off the heads of the two men on either side of the first couch.
Do this test if you have a preamplifier that can be switched by remote control from stereo to mono: Listen to a music selection which has excellent stereo separation and then switch back and forth between stereo and mono. When I do this test I find that musical details that were vivid in the stereophonic rendering disappear in the monophonic rendering.
Look at the men in the second and third rows. What kind of stereophonic image, if any, do you think they were getting? Collapse of a stereophonic sound field can cause lose of detail (information). Doesn't your heart ache for the poor soul in the green shirt on the third row?
Question 2: Stereophonic playback is a fragile illusion. When an evaluator is sitting in a compromised, "squashed", and no longer truly stereophonic sound field, is it reasonable to expect that said evaluator would provide accurate data?
Question 3: Would not it have been better for each participant to sit in the optimal sweet spot in succession and then record their listening impressions? The way the test is rigged in Figure 1, each participant is hearing a very different rendering of the music based not only on their individual hearing biases, but also on their compromised, sub-optimal listening position.
I get a wide, deep, holographic sound stage from my two channel audio system when I am seated in the stereophonic sweet spot. However,
1. If I stand up at the "sweet spot" listening position, I lose some audio details.
2. If I stand or sit along the wall behind the "sweet spot" listening position, I lose some audio details.
3. If I sit or stand to the far left or far right of the "sweet spot" listening position, I lose A LOT of audio details.
4. Is someone is seated next to me while I am in the "sweet spot" listening position, I lose a little or a lot of details, depending on the size of the person. A person sitting next to me also diminishes the tactile sensations coming from the sound stage.
Figure 2. "Can We Hear Differences Between A/C Power Cords?" - No, I don't think you can.
The referenced ABX article is titled "Can We Hear Differences Between A/C Power Cords?". The first time I saw the article and the picture of the test participants, I thought it was a tongue-in-cheek parody because obviously, you cannot do a serious, valid evaluation of differences in stereophonic audio system gear with a compromised stereophonic sound field.
Figure 3. The wizard is hiding something behind the curtain!
Figure 3 shows that the audio system and the power cables under evaluation were hidden behind a thick fabric curtain, which extended into the speaker plane. Putting a thick sound absorptive panel (like a rug) on a hard floor in front of the speakers is usually a good thing. Putting a thick sound absorptive panel (like a curtain) between the speakers is usually a no-no and bad ju ju.
Question 4: How many of you do critical listening with a curtain along the front plane between your speakers? I've never tried this, but I do not think I would like it.
Figure 4. Some seriously nice high end gear was behind this curtain.
It was a pity the test participants heard a crippled and compromised rendition of what such high resolution gear is capable of. Curtains in the speaker plane and multi-row seating? For a critical audio review? Really?
An ABX test was conducted purportedly to evaluate audible differences in power cables.
An absorptive curtain was placed in the speaker plane between the speakers.
The evaluators were seated in a manner which is highly detrimental to the the realization of a stable, focused and detailed stereophonic sound stage.
The participants in this ABX test achieved results that were statistically similar to guessing, which indicated that there were no actual audible differences among the power cables tested.
Please remain calm, civil and informative in your responses. This is a serious inquiry regarding one of the pillars of power cable naysayer science.