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

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.

EMI testing requires a Faraday cage.  The video with the FFT analyzer testing the effectiveness of a PC on an amp is fun to watch but keep in mind that this is a comparative test.  Like when we listen to a stereo component, we compare it to something else we have heard- be it live music or another component.  That is a subjective evaluation.  What this guy in the video is doing is also a subjective evaluation but with an analyzer.  Just because he has a computer outputting numbers does not make his comparison less subjective than someone doing a listening test.  Many people with highly developed listening skills can match or outperform measurement equipment.  Especially because we don’t always know what to measure or how to measure it.  The guy in the video could do the same tests again on a different day and get different results depending on the state of his power grid and local interference in his area.

An objective test must start with a baseline that is calibrated and repeatable.  That is why EMI testing requires a Faraday cage.  That is the EMI equivalent of an anechoic chamber.  That way even his test equipment is isolated from outside influence.  

I’m not knocking comparative testing.  We often have no choice and comparative listening is how we make purchasing decisions.  Item A sounds better to us than Item B and so we are satisfied with our purchasing decision until we hear something better.

I heard a difference in different PC’s and I hear a difference with and without one.  That is how I made my purchasing decision.  If I can’t trust my ears who can I trust?

The problem is that too many variables exist to definitively say this PC will make this system sound better in this way or another system will sound about the same with or without the PC.  These manufacturers are making a product that reduces line noise.  If it makes the audio system sound better, that's almost a side effect.  

Published measurement data of these PCs might be one way to show that they are working but how they affect the sound of an audio system is almost incidental.  For example, plugging an amp into one could make the amp sound worse because it limits current.  Measurements can only go so far.

Supposing you bought two different cakes from two different bakeries.  You take those cakes to a chemist and have him analyze them.  He gives you a list of ingredients and relative weight of each ingredient.  That analysis might give you some idea of the flavor of those cakes but until you take a bite, you will not know how they taste.  Furthermore, the chemist cannot tell you how each cake was mixed and baked- the process.  And the mixing/baking process could have a significant impact on the flavor.  

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.

Another thought is that in order to publish performance data and avoid litigation, manufacturers must maintain a test lab’s certification and calibration and possibly have their test results certified by an independent laboratory.  That is not cheap.  It likely becomes a business decision of cost/benefit.  Unlike U-tubers who do their off the cuff tests with possibly uncalibrated/uncertified equipment.  At least I have not seen any of them publish their certifications in the footnotes or in their videos.  And furthermore, they should state that their data is for reference only.

Another thing about power conditioners that I found with regards to audio performance is that power cables still matter.  I bought my Niagara and Hurricane power cord and experienced a significant improvement in sound.  No question there.  My front end components are plugged into the PC, not my amps.  So I assumed that my good, not great power cords on my DAC and preamps were good enough.  After all, for this kind of money this PC should have been the end game- or so I used to think.  When I decided to try a higher level power cord on my DAC I was both surprised and disappointed at the improvement it made to the sound of the DAC.  This higher end power cord reduced the noise floor even more as well as making the DAC sound even better.  Now I had to upgrade the power cords on my preamps and the better power cords improved the sound.  So don’t expect the power conditioner alone to do it all for you.  

Deep_333, I know what you are saying.  We had some test equipment that has to measure in the 6 ma range.  These stands were decades old but suddenly we could not get a quiet enough signal to pass final test.  My theory was that the new solar farm less than a mile away was the culprit but I will never know.  My test engineer wanted ground rods sunk next to each test stand.  I had to have some long discussions with our facilities Engineering Manager to get his approval.  He was convinced it would be a waste of effort.  The stands were working fine before, blah blah blah.  Well, the ground rod worked.  They had to drill through the shop floor and then sink the ground rods while avoiding a 400 amp service trunk.  Yikes. 

What will you do with the attenuation performance data of a power conditioner, if you ever get it?  Will you have the power coming into your home analyzed to determine the best fit power conditioner for your needs?  Is getting this performance information an academic exercise?  Or more importantly, are you concerned that a manufacture has significant product variation such that copies of the same power conditioner will affect the sound differently in your system?  Has anyone ever done such testing?  I know camera lenses can have significant variation among copies such that some people will order multiple copies of the same lens and keep the one they like best.  

Otherwise, published specs do not mean much to us (or is it we) end users except for application specific specs like amplifier power at 1, 2, 4, and 8 ohms or the input/output impedance of a preamp or amp.  A speaker manufacturer typically provides efficiency, frequency response measurement data and impedance curves but they do not provide information on the individual drivers used or the tolerances of the component values in their crossovers.  

Also interesting might be how much filtering amplifier and DAC manufacturers design into their products.  That is not typically listed in their specifications although some will tout their copper plated metal chassis construction or such; but still do not specify the difference it makes in noise rejection.  

Reference page 14 of the Niagara 5000 Owners Manual which can be found online.  That seems to list some of the noise reduction specs that you are seeking perhaps.

Actually, I study the owners manuals online of products I am considering purchasing.  My brother says the owners manual/assembly instructions are just one engineer’s opinion.  My brother breaks things a lot.

I don’t see any Furman power conditioners on your list audio_phool.  That’s a well known name for power conditioners.  In fact, I had a Furman PF15 elite on my stereo system for several years.  I tried it with my big Pass Labs X350 amp that I had back then but it didn’t work well with the power conditioner.  So I leave my amps plugged directly into the wall.  

I brought home the AQ Niagara 5000 with a Hurricane power cord to audition with my current stereo two years ago.  It was quite a step up in sound for me.  Despite being very expensive I kept it.  So I moved the Furman power conditioner to my Home Theater system.  I was using just a MP Surge protector on the Home Theater system.  The Furman power conditioner amazed me by how much it improved the television picture.  The colors are brighter and richer and the images much sharper.  My experience with these two power conditioners has been quite positive.

If you can find a way to correlate sound quality to specifications- especially EMI reduction specs, more power to you.