how can a line cord affect frequency response ?

The engineering types are the ones who give you your music Ronniekoh.
The marketing types love your paranoia.

Ronniekoh,

Why is it always the electronic ignorant that defend their "bat-like" hearing as gospel, and completely ignor the fact that ALL of their audio equipment was "ENGINEERED" based on decades of electronic research. You'd still be beating sticks together if it wasn't for engineering! Those silly idiots down at Pass, Krell, Levinson, Sim, Wadia, etc. Why haven't they gotten on board with all this vast PC knowledge on Agon? But I'm sure YOUR vast knowledge can run circles around their years of combined experience. Speaking of crystal-rubbing, UFO-watchin' "religious types"... Give us a break!

Regarding:

Those silly idiots down at Pass, Krell, Levinson, Sim, Wadia, etc. Why haven't they gotten on board with all this vast PC knowledge on Agon?

If you've visited their CES, HE and Euro shows during the last few years, you would find all these guys are using aftermarket high end power cords, interconnects and speaker cables.

Many use aftermarket equipment stands, isolation feet and other accessories as well. Anything to help with the sound.

It's unfortunate when responses become so emotional and even vicious. As an EE myself, I too lived for many years believing that power cables were minimal at best to not just provide an improvement, but demonstrate a difference between two models. And after trying various power cable models, mainly NBS, PS Audio and Electroglide, I still could hear very little difference compared to "stock" power cables with the Aesthetix Io/Callisto preamp, Manley Ref DAC and CAT JL-3 amps. If anything, these models stand out in their respective classes as having way over-engineered power supplies. The output transformer alone in one CAT JL-3 amp dwarfs the power supply in most power amps. And this has much to do with this amp being the most dynamic amp I have heard by quite a stretch.

The electronics masters who have contributed to this thread would conclude that I did not hear differences because the power supplies here were already engineered to respond or compensate for any differences brought on by different power cables. Such a conclusion would only be due to ignorance as I quickly learned for myself.

After being constantly nagged by two local audiophile buddies, one an architect and another a physician, who said I needed very much to try a power conditioner (PLC) and then follow this with further power cable trials, I took their advice. Was I not the electronics engineer here? What could an architect or physician know about the affects of these products that I could not know? Afterall, I went through all the circuit analysis, power transfer, control systems, amplifier design, etc., courses.

Well in a nutshell, I realized how right they were. With three dedicated circuits for the system, one for each amp and the third for the sources and preamp, at $2k, the Audio Magic PLC brought on more of a refinement in terms of noise reduction and vastly improved resolution that no other component change had ever done in my system. The only unfortunate circumstance about this experience was that I had not listened to these two people sooner.

Two months later they both came over with quite a load of power cables for a shootout in my system. The differences now between power cables were dramatic. I could see them looking at me and silently saying, "I told you so". This long-time closed-minded EE had experienced how significant power cables can affect some of the most impressively designed audio components in the business, and to take the system's performance to levels I had not known were possible with these products.

For me now, I could not care less if someone else out there can not hear a difference in such cables. Their results are due to any number of reasons. But their lack of hearing this only indicates that the cables make no difference in the context of their system. The bottom line is that there are differences and they are often not subtle. If you need to go back and forth over and over to try and hear a difference, then plain and simple, your incoming power is a mess or your system's resolution is just not there yet. And for such a case, put your money elsewhere and repeat the power cable trials every couple years or so. I did, and finally it paid off. Just putting a pair of Purist Dominus power cables on the CAT amps brought explosive dynamic contrasts compared to the other power cables I had here.

As for the response by Mrtennis, "but it can not be verified", oh yes it can. Perhaps not in your system can it be verified, but in the context of many others it certainly can be. So many people in this thread have already concluded the outcome without putting forth the effort to hear the possibilities in a highly resolving and dynamic system. I can relate to such an attitude as I lived it myself on the issue of power cables for many years.

We can believe what we want to believe. And we can preach all we want about what we know due to our experiences and education. But one thing I am very grateful for here on A'gon is the amount of knowledge and experience I have gained by others who were more open minded than I was.....and I was the ultimate beneficiary as they had nothing to gain other than witnessing my happiness from the changes.

Oh and one more thing - do power cables affect frequency response? Go drop a Purist Dominus power cable on your favorite power amp, or DAC or preamp for that matter, and make note of the bottom octave presence and control that was not there before.

John