Any one measured the EMI/RFI attenuation performance of audiophile power conditioners?


I was looking for a very good/robust power conditioner which will clean up reliably very noisy/dirty power supply that I have in my aprtment. While looking for one I went through catlogs of AudioQuest, Shunyata Research, Synergestic Research etc. but no one published charts showing attenuation performance over frequency range like you get for EMI filters from Schurter or Schaffner etc. which are in the industry for EMI/EMC compliance.

Since audio is very subjective, but contrary to audio reproduction Power and EMI/RFI reduction is completely objective and can be clearly demonstrated via attenuation charts.

Hence I am asking if anyone has measured the actual performance of these audiophile power conditioners. I am not denying someone saying they hear improvement after using XYZ product, but since I am talking about power conditioning or EMI reduction it's as objective as it can be.

I am not at all surprised to see all the manufacturers not publishing the performance data, else it would be used in other industries and research fields where it's far more critical and have far more stringent requirements on the performance of conditioner/EMI filters. But I am shocked to see even products ranging above 5-10K are following the same practice of not publishing the results.

Please note I am not a measurement fanatic, but I know where I can chase the measurements and where I can rely on my hearing to gauge the difference.




My first thought is manufacturers of PC’s prefer to keep their performance data proprietary as much as they can.  Why give their competitors easy access to performance data or also, it becomes a specification contest with no connection to sonic performance.  

I worked in Automotive where our products had to meet EMI/RFI emissions per the SAE and DIN specs.  I do not recall specifications or standards for devices that attenuate EMI/RFI.  Maybe I am wrong but that leaves noise conditioner designers to find their best design paths to meet performance or audio goals.  But without measurement or industry performance standards the claims and measurements of Power Conditioners with respect to we consumers could become very confusing.   It is already confusing for us because results vary between applications, local EMI noise conditions and how our unique audio systems respond to PCs.

You can do swaps/blind ab in my room (with my streamer+DAC+amp) between my Audioquest Niagara and wall. I have in the past and will point out over and over, 30/30 times (to statistical significance). It is that freaking obvious to my ears!

These type of recurring threads are tired and ignorant.

I know, it's like talking about the weather.  I have the Niagara 5000.  It is also an obvious improvement for me.  Expensive and not as much fun as buying an amp, DAC or speakers but the improvement in sound is unmistakable for me.


I’m not well versed in power line noise and the resulting issues with a systems sound quality, but I thought that noise at 1Mhz was preferred to noise within the auditory frequencies and that such noise could be easily filtered.  Power conditioners and systems of conditioning like with Shunyata, or Audioquest claim to also limit noise generated by component such as switching power supplies.  So, I’m not clear on why filtering of 1 MHz signals is a key point of your post.

Audio consumers have complained for decades that power conditioner manufacturers don’t publish object measure of their products direct impact upon what we hear through our electronics.  Has anyone quantified what attributes must be measured and how they are measured?  I purchased the Everest and associated power cables on a ninety day trial and didn’t return it because it was the single greatest improvement that I had heard in my system to that point.  I recognize that this is subjective, but what group of measurements can be used to predict the listener’s subjective experience?

@tonywinga I don't understand whats in the performance data which needs to be kept secret even though the method of achieving the performance can be proprietary and hence method can be kept secret. In fact performance numbers are a thing to boast & if I was the mrketing head i will use them everywhere to market the product unless they are terrible & hence need to be kept secret.

Your example of Automotive industry exactly confirms the point which i said, except for the Audiophile industry, every other industry has standard norms and specs to be met, else the product is useless. In audio while sound is highly subjective and hence cannot be standardised the way it's done for other things, power conditioning or EMI reduction is something very well established & measurable thing, yet audiophile grade manufacturers of these products choose to ignore the specification and/or performance data.

@deep_333 I never said any of these products don't make the improvement/changes to the sound. My post was regarding lack of objective measurements/performance data for something which is completely objective. Will FDA accept a new drug if tomorrow the manufactrer will just say I saw improvement in a patient's condition?