When we set out to prove one thing or another we arrange tests to prove our theory.
For example, if you’re trying to prove there are no differences between cables or amplifiers there are any number of ways to prove that. One would be the difference or null test where an identical signal is passed through two samples: say an expensive audio interconnect vs. a cheap one. If there were actually a difference it would show up on the scope as such.
Since we know that changing input cables—a high-end version vs. a dimestore copy—on a power amplifier in a highly resolving system is easy to hear, the null test should show the difference. Yet, it may not. Do we then conclude there are no differences?
If our goal is to understand why we hear a difference then it’s incumbent on us to dig deeper. Our hypothesis didn’t give us the results we were looking for. Our ears detect a difference our meters and methods fail to uncover. The proper conclusion is not to stop there but to march forward until it can be satisfactorily explained.
Garth Powell of Audioquest proposed a method that just might have some answers. Since the change we hear comes out of the loudspeakers and affects the entire audio chain, it’s only logical we measure the entire chain to seek differences. This would involve using a microphone to capture the output of the system and then comparing the recorded files to find the differences. It’s essentially the same test I have done any number of times with the microphone in my iPhone which more than adequately picks up differences.
I haven’t the time nor the interest in performing these tests with any scientific rigor, but perhaps someone else wants to grab the flag and climb the mountain. It would have to be performed on a system where we actually do hear a difference.
Proving what we already know might be valuable to someone.
Just not me.