how can a line cord affect frequency response ?

back to your original question, I have a hypothesis(not a theory) on why a power cord would affect frequency response.
1)Almost all well known audio component manufacturers pay special attention to their power supply with their flagship products. The topline normally differing only in the power supply and delivery to their second in line.
2)Almost everyone also recognises that transformers and filter caps play an important role in the final sound and these falls within the power supply section as well.
3)I believe that human hearing is more sensitive to phase differences than tonal differences.
4)Given that any conductor carrying a current is going to generate a lateral motion in a magnetic field, capactance and inductance is inevitable.
5)In any pc, it is relative straight and would vibrate, the vibrational and dampening aspects plays a huge part in its sound, the same with tranny or caps. Not to say that the type of the conductors or the shielding does not matter, but I believe that vibration tuning plays a significant part.
6)the same pc's sound different in different setups because they are placed differently(coiled, draped on lifts, on the carpet etc) and hence their vibrational aspects are affected.
7) I divide pc's into 2 main categories, modifying and neutral. eg, elrod vs cardas. modifying cords affect the sound whether they are at the breaker or just before the component. I use both types, which you prefer depends on your biases and your overall system sound.
8) Other aspects such as geometry, guage, shielding, material, dielectrics, conductor cross sectional shape, length, connector types, termination, treatment, conductor state(liquid vs solidvs amorphous), length etc is left out for another day in this post as they do matter as well.

regards

John,
well said.

Two weeks of theory is not going to convince someone who just heard a difference in the first 5 seconds of swapping. Justify all you want. Only hearing the music matters to me. Does not really matter if it is a placebo effect or what. I hear a difference is all that matters.

below is a message bet I sent several yrs back
I just had an argument with a techno type about
cables.
Done it many times, its interesting.
He said that cables do not make a difference. (Of
course he is the engineer type who prefers the low
cost solution backed up by theoritical claims that
never faces the acoustic reality of the products that
he supports)

So I brought him over to my house and switched out
thin monster type cords vs a cheap pair of ps audio
speaker cables(I don't even want to show him my real
ones).
Guess what, he heard a undeniable difference,
which he then justifies by saying that the gauge size
is different and therefore the resistance is lower and
that makes a difference. So I asked him that if the
guages were the same, then they would sound the same?
He said YES!
I then asked him if one were silver and the other were
copper, would it make a difference?
He said since the conductivity is different,
the answer is YES!
So I said if the gauges were the same and the same
conductors were used, there would be no difference?
He said YES!
I asked again if the above two were the same but if 1
was a twisted pair(or coax) to better reject
interference and the other was not, would there be a
difference?
He answered, anyone would know that a twister pair has
better noise rejection so,
the answer is YES!
So I said that if the conductors were the same, the
gauges AND the same geometries were the same, then
they would sound the same?
At this point, he suspects a dead a end trap and he
pulses a long time before answering...
Yes ....
So I carried on, I asked if shielding makes a
difference? He's cautious now, and answers, if in a
noisy environment (like near power transformers ...),
yes ...
So I said "in order for cables to sound the same, then

all of the above must be the same? in which case you
must have the same cable! RIGHT?"
he went ....
While he was quiet, I gave hime a couple more things
to think about, like dieelectric, vibrations, skin
effects, termination, static, etc ...
He came back and said well, maybe they are not
audiable ...
at which I replied "you must be deaf or in denial"

looks like this is the same study with PC's

Oh, forgot to mention, next time l went over to his house, he was using oval 9'S . Now he is using Nordost Heimdalls & VD power 3. Now, he is lusting after my Siltech Sig & Khamas. YmMV

Don't you notice that it is always the engineering types who feel a need to justify by first principles the sound of his system to others when all he has to do is start the music? or do they think that all that talk before hand is going to make it sound any better? reminds me of the religious types who need to convince others to shore up their weak faith ...
Build your products with your theories, the heart and ears will be the ultimate judge. Theory and execution are two different things, only results matter.

bravo tvad,
just when I thought this thread is getting boring again...