Power cords

Many power line filters are placed "in series" with the existing wiring also. Their benefits are easily noticeable under specific conditions and measurable if you have the proper test equipment.

As such, a smaller amount of "filter action" can be designed and built into a power cord. This too SHOULD be measurable. One of these days, i'll finish up the mods that i need to do to my Audioprism AC Sniffer and do just that. Until then, i do not doubt that a power cord can effect the quality of AC being fed into the component. I too was a skeptic until i tried it for myself. Sean
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I doubted. I tried with the option to return. I was convinced. I added another with the option to return. I was convinced. It is certainly worth a test drive.

The only measurement that is truely relevant to this discussion (and that is almost never performed because of its cost) is a statistical analysis of a psycho-acoustic experiment properly designed and executed. All our electrical test equipment only gives us a hint of what our ears and minds are capable of perceiving. -- And yes I have an MA in psycophysics specializing in acoustics. That leads me to believe that anecdotal evidence, based on perception, even without an experiment is worth paying attention to. In fact, I would guess that many designers of high end equipment base what is unique about their designs, in the final analysis, on listening rather than electronic measurement (what good is it if you can measure it but cannot hear it).

I don't mean to suggest that we haven't learned a lot from these imperfect measuring tools or the mathematics that go with them. I'm a strong believer in correcting room anomolies as much as possible and even use digital eq to good effect (so much better than the old filter approach). But ultimately we're talking about music/sound which is perceived by a listener, and the listener is what counts.

What I find strange about many of these kinds of discussions, is that participants often pit electronic measurements against human anecdotal evidence. If your skeptical about anecdotal evidence, the answer isn't to turn to a useful but imperfect machine but rather to properly perform psycho-acoustic experimentation.

I can't see (hear) where scientific measurement matters. For example: This thing has gone on with string instruments. People have made hundreds of scientific measurements and made perfect copies of Stradavari instruments. They still don't sound as good even though scientifically on paper there is no reason why they shouldn't be as good. If they could reproduce them, they would be massed produced by now in China, and be available for 5 easy payments of $19.99 on the home shopping channel.

Power cords act as antenna to RFI and EMI. The ones that are specifically designed to reduce those influences, through cable geometry and shielding, can improve the sound over cords that don't pay attention to it. That's why the 'last six feet' of wire can matter. Now if there isn't a lot of RFI/EMI in the first place in your environment, or if your system has a lot of noise in it anyway, well then, you may not notice much difference.