I would urge some caution in making broad sweeping generalizations based on the results. If, on the one hand, a group of listeners can detect differences in outlets, that demonstrates that under certain circumstances, the effects of outlets can be audible. It does not imply that all listeners will here differences under all circumstances. On the other hand, I'm not sure that failure to obtain a statistically significant result in the test means that it is impossible for such audible differences to be heard under any circumstance.
With respect to the test itself, If possible, I would prefer the listeners not hear the tests collectively. It is difficult to ensure people are not being influenced by others. I would proceed first with a quick A/B, (better, worse, no/little difference, then proceed with A/C. C/D, C/E, etc retaining the preferred choice for each A/B comparison. As one proceeds through the test, roll back into the A/B a rejected outlet to see if the perceived preference is retained.
Whart offers good comments about comparing outlets that are close. That would require more extended listening.
My experience would lead me to expect that there could be obvious problems with the cheap outlets, but perhaps less obvious differences between outlets prepared and marketed for audio use.
With respect to the test itself, If possible, I would prefer the listeners not hear the tests collectively. It is difficult to ensure people are not being influenced by others. I would proceed first with a quick A/B, (better, worse, no/little difference, then proceed with A/C. C/D, C/E, etc retaining the preferred choice for each A/B comparison. As one proceeds through the test, roll back into the A/B a rejected outlet to see if the perceived preference is retained.
Whart offers good comments about comparing outlets that are close. That would require more extended listening.
My experience would lead me to expect that there could be obvious problems with the cheap outlets, but perhaps less obvious differences between outlets prepared and marketed for audio use.