Conclusions
To many in the engineering community, blind ABX is an accepted experimental design. Using the blind ABX protocol, we failed to hear any differences between an assortment of generic power cords and Nordost Valhalla. Therefore, we cannot conclude that different power cords produce a difference using the blind ABX protocol. However, we also cannot conclude that there are no differences. We simply failed to prove that differences can be detected to a statistically significant degree using a blind ABX protocol.
John Johnson, who comes from a scientific background, suggests that if there are differences between cords, they appear to be so subtle that a blind ABX test cannot discern them with small numbers of participants. Failure to discern them could be due in part to the time it took for cable changes, and the possibility that accurate auditory memory is shorter than that. It may be necessary to switch between cords in a much shorter time.
Unfortunately, as John notes, we don't know of a way of accomplishing fast power cable changes, since, unlike interconnects which can be simply switched between A and B with the equipment all still powered on and playing music, changing AC power cords requires turning the equipment off, switching the cords, and then powering them back on.
The test was a grand and noble experiment at best and a bust at worst. Make of it what you will.
Editor's Note: ABX tests are valid and do work. Here is a link to some ABX tests of various types of audio products. In many cases, statistically significant differences could be discerned by participants. In others, no differences could be discerned. http://www.pcavtech.com/abx/abx_data.htm. Now, of course, one can dissect an experiment and say, well these 4 people out of 10 participants had good scores, so they could hear the differences. But, no, you have to take all the data together. You can't just pick out the numbers that suit your hypothesis. This would be statistically invalid. Same thing with just looking at one music selection. With statistical random patterns, it is likely that there will be one selection where more participants score correctly than on other selections. If we had enough music selections, there would likely be one where all participants scored perfectly. But, you have to look at all the selections together. That is the purpose of statistics. You may remember the famous monkeys typing randomly concept. If you have enough monkeys, eventually one of them will type all of Shakespeare's works perfectly. To look at only that one monkey might suggest it knew how to type Shakespeare. But, we can't do that and claim good science.Conclusion if it is almost imposible to hear changes in the audio chain then why throw money down a giant rat hole on pc cables that only look good and yet do nothing for sound and only lighten your pocket?
