Recently we've had two monster sized threads on DTV Forum about the benefits of specialised power cords:
Multi-Channel Audio Systems / Advice On Power Cords
2-Channel Audio Systems / Bt At Kajak
The first thread was theoretical, and included requests for blind test evidence.
The second began with a report of an informal 4 or 5 trial blind test, which was not taken beyond the 4 or 5 trials because participants considered the differences made by the change in power cord were too obvious. (The device that had its power cord changed during the trials was a custom built DAC.)
In this third thread on power cords, I invite uploads of recordings of the output of power amplifiers or other audiophile devices playing the same excerpt of music, where the only difference in playback conditions is a change in the power cord of an audiophile device. This should allow all interested forum members to conduct their own private double blind ABX test using an ABX player such as foobar 2000. [Note, the ABX functionality for foobar 2000 may need to be added after installing the basic player.]
I am assuming that comparative sample recordings do not already exist on the web. Certainly I have noticed no sample recordings on websites of manufacturers of specialist power cords. If they already exist, they could shed light.
I suggest recordings be made at a sample rate of 48KHz to keep file sizes manageable. Recordings at a bit depth of 16 would be ok, but some people may prefer to record at 24 bits (provided of course the stereo ADC allows it).
With each pair of recordings I would suggest that the musical content of the two files be time aligned to the nearest sample, and the aligned files trimmed to identical lengths. (This can be done, for example, using the free software, Audacity.) Files should start with a short period of silence in order to facilitate later ABX comparisons. A fade in may be appropriate. The silence and any fade in should be identical for both files.
It is the practice on some forums to limit links to recordings of non public domain material to excerpts of no more than 30 seconds. I myself cannot provide any advice whatsoever about copyright and any other legal issues regarding uploads. Members should consider these matters.
I suggest that unless you can hear a difference when you play your recorded files back and switch between them (say by using the mute and solo functions in Audacity), it may be sufficient to report that outcome to the forum, rather than uploading files that sound the same. On the other hand, if you find material differences when inspecting recorded waveforms, then despite the differences being inaudible, an upload could well be of interest.
If recording the stereo output of a power amplifier connected to speakers, an attenuator will probably be required, as line level inputs to ADCs usually cannot tolerate high signal levels. For example, an 8 ohm speaker when driven with a sine wave at 8 watts will have 8 volts RMS across it. A series resistor, in conjunction with a shunting resistor across the ADC input, may do the trick. This is entirely at the risk of forum members. Warning: Don't treat loudspeaker level voltages lightly.
They can deliver an electric shock, and incorrect connections can damage an ADC, or the power amplifier itself.
As for myself, I have no power amplifier with removable power cords. About the best I could offer to do would be to make a pair of recordings with the presence or absence of a lengthy extension cord in the mains supply to a power amplifier, as the only variable.
P.S. There's a lot of scepticism regarding alleged improvements by special power cords. Below is an example of that from an April 2010 thread on AVS Forum titled: Will a new power cord actually improve performance?
The OP asks:
At post #15 of the AVS thread, a person claiming 34 years in the Electrical Contractor industry states this:
It's a scam, and people who should know better still fall for the marketing double-talk and parrot the information as if it's true.
It is only with hard evidence that this type of scepticism can be overcome, if indeed hard evidence can be found! If and when it is found, we may wish to explore what caused the audiophile equipment to perform differently.
Think about it, even with a $500 micro-strand 24K gold-conductor diamond-encrusted power cord, you're still plugging it into a residential builder's grade wall receptacle with tiny contacts in a house that has old Romex or knob-and-tube wiring, getting power from a cheap $5 circuit breaker in a panel that's getting unclean power from a transformer somewhere in your neighborhood that's getting it's power through a regulator in your utility company's local substation which gets it's power from a power plant that's possibly hundreds of miles away from your house.
Do you honestly believe that simply changing the last few feet of cable between your wall receptacle and your TV or Audio system will suddenly make your equipment look and sound better? The answer is NO.