Yeah that's some high frequency noise alright. Enough to amount to 2 db increases. And apparently there is more noise on the expensive cords too!
I had assumed you were saying some cord constructions would have less high frequency response than others. Certainly possible, but also irrelevant as a power cord.
Please try to concentrate only on the informations given in the blog:
"He did the usual things including hooking up an audio circuit to a power outlet and showing us all the incredible amount of noise on the line — noise that never gets converted into the DC power sources used in your components. This is a red herring argument. "
So we have an audio circuit hooked up to a power outlet, but we don´t know which kind of audio circuit it was.
Reportedly the "incredible amount of noise on the line was shown" but we don´t know which way it was shown; by the audio circuit? By diagrams or measurement device?
And we know that Marc Waldrep thinks "the line noise never gets converted into the DC power sources...." which isn´t a useful description; if it should mean that you can´t find the "incredible line noise" in audio components after the psu it is factually wrong.
"He then demonstrated 4 different power cords ranging in price from a few dollars (a typical IEC cable like the ones included in the box) to about $17,000 for the Nordost Odin 2 Power Cable. The two cables from his company were $750 and $4000 — a mere fraction of the price of the Nordost. I brought along a reference quality microphone and portable recording device which I kept out of view as I recorded the music selections powered through the different cables. "
Ok, four different power cords, an "ordinary one" , two from the competitior guy and one "Nordost Odin 2 Power cable" and Marc brought along a "reference quality microphone" and recording device which he kept out of view (behind his/somebody´s back? In a bag/pocket?).
He recorded the music selections "powered through the different cables" .
"As if by magic, the IEC power cord measured 2.5 dB SPL lower than the others. The most expensive cable — the Nordost Odin 2 — was louder by a substantial amount than the Dragon and Thunder cables the competitors provided. "
So the IEC power cord measured 2,5 dB lower than the others and the Nordost Odin 2 was "louder by a substantial amount " than the two from the competitor. What does substantial amount mean? Again 2.5 dB louder? Even more? So we are talking overall from "ordinary iec cord" to Nordost Odin 2 about how much 5 dB? Or an even larger range? Or was substantial lower than 2.5 dB
"When I asked the other person measuring the SPL in the room, he concurred with me. “I saw about 2 dB difference,” he whispered. "
Did he saw 2 dB difference between the ordinary cord and the others or did he saw the 2 dB difference between the others and the Nordost?
There is imo a lot that we don´t know and therefore i wrote, i wouldn´t rule out anything before knowing what really happened.