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I was surprised this cable didn't magically make everything better. I thought you buy cables like this so you can use $3 headphones and make them sound like $1000 headphones? I guess the marketing isn't clear LOL
This is a review, listening tests and detailed measurements of the JPS LABS DIGITAL AC-X FILTERED AC CORD. It is on kind loan from a member and costs US $649. View attachment 270396
I was pleasantly surprised that despite its girth, the JPS cord is quite flexible and lightweight (for its thickness). I suspect there is good bit of air in that oversized jacket. Sadly there are no safety regulatory marks on it.
JPS LABS DIGITAL AC-X AC CORD Measurements
Company advertises the cord for digital sources (I think) so I choose to test it with a Topping D70s which ironically costs the same as the JPS cable! Here is our dashboard with generic AC cord:
We have the usual run to run variation. Beyond that, there is no reduction in noise or distortion. Output level and frequency are the same. Let's run 32 tones to see if this outcome changes: View attachment 270399
It does not. So let's not waste time doing more DAC tests. Instead, let's find out if there is any filtering. The filter performance changes with impedance and I don't have a ton of flexibility in my analyzer in this regard. Still, I set it as close to what it may see in real life and got this: View attachment 270400
So there is some high frequency filtering as we often see in power products. As with previous devices of this sort, there is not meaningful amount in audible band to make a difference. Same filtering exists to far, far higher level and power inside any power supply. To show that, let's measure the output of a MeanWell switching power supply that came with the Eleven XIAudio Broadway headphone amp I recently reviewed: View attachment 270401
There is a tiny difference in favor of JPS cord. But remember, this is the "raw" DC going into the amp. Any performant amp will post filter this output and get it far, far cleaner. And at any rate, the levels shown above are down -140 dB relative to the output of the switching power supply!
As you see, they are identical. The JPS didn't remove any of this (mainly because it is internally generated in the power supply).
JPS Labs Digital AC-X Power Cord Listening Tests
I powered the Topping D70s with the JPS cord and fed its output to Topping A90 which in turn drove my Dan Clark Stealth headphone. The first reference track sounded better than I remembered! I then switched the cord to generic one and it indeed "sounded" worse. I then switched back again to JPS cord, and it now sounded the same as the generic cord! In other words, nothing but random observations here.
The JPS AC-X cord performs a bit of filtering which we can easily measure and quantify. Where it goes wrong is assuming that you listen to the AC cord itself and that your hearing extends well above audible band. None of this of course is the case. The AC cord powers audio gear which has internal filtering that dwarfs anything the power cord can do. Indeed the incoming AC is extremely "dirty" and any designer of any skill level will know to filter its output to get down to DC (0 Hz). Hence the reason the output of the DAC I tested (or any equipment you have) will not be changed one bit because you have an AC cord with a bit of filtering in it.
I did like the flexible nature of this cord although it is still much heavier than a generic cord. When I tested it with the MeanWell power supply, it easily dragged it off my table.
Needless to say, I can't recommend the JPS LABS DIGITAL AC-X FILTERED AC CORD. It works on theory rather than reality of the role of an AC cord and effectiveness of the level of filtering it provides.
As always, questions, comments, recommendations, etc. are welcome.