@bemused-- You wrote:
"From perusing the web site, ADD-Powr is appears to be about increasing "energy", or the voltage of the audio signal through the generation of harmonics on the reference supply that are too low in frequency to be filtered away by the component power supply. They more or less resonate with similar frequencies in the audio signal. If the fundamental signal is low enough, then its resonant affect will be evident throughout the audio band. The driving fundamental must be a complex function composed of sines and cosines in various phases - that is the Fourier series. Or...perhaps it can be simply be a square wave!
That explanation makes sense."
It does not make sense to me. Can you explain it? What frequency levels are we talking about, exactly? Power comes in at 60Hz. What low level AC frequency will resonate through a DC power supply?
@millercarbon--
Please refrain from obscene generalizations about people. When I say something seems like snake oil I am most certainly NOT saying that my mind is made up, that everyone else are suckers, and that I am not going to listen and learn.
What I AM saying is that when there is no rational basis to accept a manufacturer's claim as to how something works, and they provide not a shred of what should be easy-to-provide corroborating measurements to demonstrate effectiveness, it makes me highly skeptical. There are a thousand tweaks out there and my time is limited, especially I am going to spend it listening to things that have a reasonable chance of making a difference. Especially regarding improvements from AC side tweaks, which have nothing at all to do with the musical signal. Unless your power quality is terrible, AC side stuff just isn't going to make a difference. Running your system off a quality UPS will give you perfect sine wave power, stable voltage, and no harmonics. Problem solved.
For goodness sake, would you not be skeptical of, say, an amplifier designer who says their amp sounds better because it's inhabited by quantum level musical pixies?
Hey, if someone else hears a difference, more power to them, though, with the ever present caveat of awareness of confirmation bias. If you don't do double blind testing, how do you know you actually heard it? By all means, go by what you hear - I certainly do - but don't you want to be certain that you really heard it?