There are only four parameters that affect audio fidelity, and when those are satisfactory the device will have "resolution" equal to or surpassing what human ears can hear. Full story here: AES Damn Lies --Ethan

You said you're an electrician, so this is more for others reading: What can be seen at the end of a power cord on a 'scope is irrelevant. All that matters is how the connected audio device is affected. Even if there's several volts of noise and RFI riding on the AC line (unlikely), and even if...

It's useful to define "distortion" first. Some people consider any change to a signal to be a form of distortion, but generally, for audio, distortion implies nonlinearity. So in that sense equalizers don't distort beyond small amounts of residual distortion in the analog electronic portion of a...

I tried mixing in a pure 200 Hz sine wave with both the original and reversed versions, to see if that countered the apparent pitch shift. The result was inconclusive. It sort of did and sort of didn't. The shift is so slight it's barely audible anyway. I'll think about this more and play with...

Maybe I didn't understand because I'm not a math type. I got the file you sent, and I see that you simply inverted the polarity. So now we're on the same page. For the benefit of others here, as I said in my email back to you: The tonality of the normal and inverted sections sounds identical to...

But that's shifting only some of the content in a file using an all-pass filter, which is not the same as polarity reversal which reverses everything regardless of frequency. I missed that because the link was within a quote, which I thought was you quoting someone else in this thread. I just...

What amplifier or other audio device shifts 800 Hz by 180 degrees while leaving 400 Hz alone? Further, that shift is benign unless you combine the source with the output, which would never happen. You're really reaching here. :D Phase shift can be audible if it's extreme, such as many...

The resistance of wire is so much lower than the connected devices it's not a factor unless you're talking about 50 feet or longer, or using stupidly thin wire. It doesn't matter. --Ethan

I'm not promoting that people honor or ignore absolute polarity. My entire point is simply that it's not audible, and when it is it's due to the speaker drivers and not how we hear. That article addresses all-pass filters and their frequency-selective phase shift. That's not usually audible...

I listened only to Sample 2, normal and then inverted. They sound the same to me. I listened on decent quality Sony headphones. Usually a difference can be heard after inverting polarity only with low frequency content. And as I explained earlier, it's due to non-linearity in the speaker or...

Sure, and I certainly didn't mean to disagree with you! --Ethan

Even that is dubious. Phase shift per se is inaudible in typical amounts. It's a total non-issue, a bogeyman invented by audiophile magazine writers to explain stuff they don't understand. --Ethan

Here it is on YouTube: https://www.youtube.com/watch?v=cIQ9IXSUzuM

I'm with bigshot on this. Even if you played music at earsplitting levels you'd never reliably tell one amount of crosstalk from another because both are way too soft to hear. Again, if only you would do a proper test you'll learn at what levels you can hear artifacts such as distortion and...

Ah, the old anecdotal evidence. Do this test again in a controlled fashion, and blind, and you'll find that frequencies higher than people can hear have no effect at all on the sound. The notion that ultrasonic frequencies must be captured and reproduced is the hold grail of audiophoolery. If...