how can a line cord affect frequency response ?

I only would make one comment, and that is to say to buy and listen to what you like and want.

In the end, you only have yourself to please, as it is your system, and nobody else's.

Please, I would implore any people seeking to measure the performance of anything "audio", to at least measure it in the context in which it is used, so that we don't have the mess that occured in the past.

I noticed that a very well-meaning poster above sought to use a steady sine-wave test tone and a load resistor in his testing. Is this not what got us into this mess the first time? Doubtless, negative-feedback-equipped power cords will result!

If someone is "hell-bent" on having some numbers to "lean on", then please try to procure them in a way that is meaningful to the way the product is operated when it is in its intended use. The idea(as I see it) is to find out something useful, and not to "make it easier" for the measurer.

Personally, I think that something may come of this, and I would love to see some new measuring protocols introduced that could address this common topic of why we don't seem to be able to measure the observations that we are obviously hearing.

You can't do this "in a vacuum". It needs to be done so that it measures the things you want to find out when the product is operating in the listening environment, playing real music. "In-situ", as it were. Test tones and "dummy loads" are out of the question. It is what happens in the actual reactive environment that we need to know, and test.

Dpac996,
I was joking about the "negative feedback power cord", because of the past history of what happened in measurements to product that end in audio amplifiers during the 70's and 80's.

I'm actually pleased that you are interested in doing things to help us understand what we want to know.

I only qualify that with the hope that the tests are done in such a way as to ensure that past mistakes are not repeated.

Eldartford,
I'm glad that you are looking at ways that could advance what we know about testing audio products, and making those tests as relevant as possible to the real-world operating conditions of the products.

I feel that doing those kinds of tests, and even coming up with newer test protocols to accomplish this would get us further toward the truth about what we test and hear.

While I've been accused by others(not you) of being "unscientific", I actually have no beef with science. I only want the tests to be as accurate as possible in determining the outcome, so that we can ensure as far as possible that no incorrect conclusions are drawn from the tests, as has happened in the past.

My aims are to reveal as much truth as possible, and not obscure it.

Shadorne,
I've been using solar power to re-charge my battery operated system for years.

Just for a little aside to the discussion here, I don't use "audiophile" AC power cords. My system is battery operated on DC power.

And I use a separate 12vdc lead-acid type battery and very short cabling for each individual component. There is no interaction between the power supplies of my components, except for whatever interaction occurs between the components themselves via the interconnects. My amp power draw has no effect on the power supply to my preamp, or to my turntable, and vice-versa. Also, high-voltage electromagnetic fields associated with the AC power supplies is virtually eliminated.

I find this works very well for me, but may not be suitable for others, especially those with high power audio systems.

Eldartford,
My stuff is made for battery power, and there are capacitors in the power supply, and I do keep my wires short to try to minimize the inductance issue too.

To answer your question, I have not noticed any change or difference if the sunlight on the solar panels changes. However, I mostly do my listening in the evening when there is no sunlight, so I don't know for certain if there might be any audible changes resulting from the varying voltage coming from the solar panels into the batteries.

In the case of my turntable, the way the battery power supply works is by actuating a relay that disconnects the charging ciruit when the TT is running. This is because the TT battery option is designed for normal homes using AC power. But I can also use it in my application.

Just to get another opinion here, what do you think might be the effects of different component's power supplies modulating the power lines(and therefore the other component's power supplies), and possibly causing some noticeable effect, especially high-power amplifiers that suck alot of juice? I admit that I am only going on a hypothetical idea with that. But I thought it couldn't hurt to keep all the power supplies independent of each other. Do you think this may be something that could use a closer look in our home audio systems?