This is a review and detailed measurements of the AudioQuest NRG-X3 AC power cord. I purchased it a couple of years ago for testing and costs US $99.95.
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The cord is 16 gauge and is more flexible than my thicker freebie AC power cords. The mating ends connect perhaps a bit more solidly than my generic code. I think the terminals look ugly but they work.
There is no mention of any regulatory certification, UL or CE, on either the cord, box or the website. My generic AC cord has UL stamped at one end and the cord itself. It also has more specifications as far as insulation type, temperature rating, etc. which the Audioquest lacks. I am curious how they export it to EU without CE certification.
I was "delighted" to read the feature list of the NRG-X3:
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We know how to measure both distortion and noise. And company clearly cares about both factors.
My sample is 2 meter and the generic one is what I have on hand at same length.
AudioQuest NRG-X3 Measurements
I started by measuring the DC resistance of both cables. My generic cable came in at 0.13 ohm whereas the AudioQuest was better at 0.02 ohm.
Next I decided to measure the distortion in both cables. To do that, I terminated the cables into IEC sockets at both ends and ran them into the differential outlets of my Audio Precision analyzer. Let's start with measuring the Audio Precision itself without any cable with 20 volts output:
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As you see, I used 60 Hz as the tone to mimic mains frequency. Despite the high output voltage, performance is superb with distortion below -140 dB and SINAD at 120 dB. Now let's measure the generic AC cable (treated as a signal cable):
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There was some variability and slight rise in distortion at 180 Hz. Considering that we are treating an AC cord as a signal cable, this is extremely good result showing that there is little distortion to worry about in a power cable. In a pinch, this generic AC cable is as good as a balanced cable!
Let's now switch to AQ NRG-X3:
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The harmonics were dancing up and down. Within that variability, I think we can call this a tie. There is no reduction in distortion using the AQ cable.
Someone may say that one cable is better than the other in high frequencies so let's expand the bandwidth to 1.2 MHz and see if there is a difference there:
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Nope. They are the same.
I then ran a reverse leakage test. I brought a transformer near both cables in the above setup and captured its AC noise and distortion (changed the drive frequency to 1 kHz to make that easier to see):
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We see that both have similar susceptibility to magnetic induction. This is an extreme test though. Move the transformer an inch and all the interference disappears from both cables.
As usual I like to remind everyone that we don't listen to AC cords directly. We listen to output of our audio gear instead. So let's grab the last DAC I tested, the Topping DX5 and let's see if the performance varies between AC cords:
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It doesn't get more identical than this.
Let's switch devices and use the AC cables to power an amplifier, the recently tested Audiphonics HPA-S400ET:
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Again, you couldn't get more identical results. The two graphs have landed on top of each other perfectly.
Conclusions
Company advertising for NRG-X3 is very specific with respect to reduction of noise and distortion. No matter if we test the cable directly or through a piece of audio gear, there is no detectable difference despite the incredibly precise nature of our measurements. This makes statements like this from the review of said cable by Stereophile quite dubious:
"The AudioQuest NRG-X3 delivered more music, made more sense of the music, managed to more fully convey the artists' intentions, and made me a happy guy."
Making more sense of music? Fully convey artists' intentions? Good grief.
Lack of safety standards is a concern. We don't know the abrasion resistance, temperature rating, etc. either. So better not run over the cable or place it next to hot items.
On the positive front, the cable does seem to have lower DC resistance and is flexible. And at $99 price I paid, it is not hugely expensive. So if you bought one, I am not going to chase you. Personally I have better use for my money than spending it on power cord so
can't recommend the AudioQuest NRG-X3.
Edit: video review posted as well:
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