Performance above 20kHz matters

Fact or fiction? Does amplifier performance above 20kHz matter? This question came first in our list of Fact or Fiction because it's a fairly easy one to answer but the answer's going to piss off a whole bunch of objectivists. Let's try and fix that so everyone wins. To an Objectivist, 20kHz and above does not matter for one plain and simple reason: humans cannot hear above 20kHz. Ergo, if we cannot hear something then it doesn't matter. Case closed. While the base statement is accurate, it ignores the consequences of implementation. If we instead look towards the practical application of high bandwidth amplifiers we see that we could ask a very different question and get a very different answer. The right question to be asking is this:

Does phase accuracy matter within the passband of human hearing?

Now we have a proper question that circumvents all the narrow focus arguments that plague us. The answer to question 2 is an unequivocal yes! Human hearing is very sensitive to phase differences within the audio passband. Circling back to the first question, we can now answer it with another unequivocal yes! because there are no practical means of bandwidth limiting an analog amplifier to 20kHz without affecting the phase. It's typically important to have a bandwidth approaching 100kHz to get phase accurate performance in the audio passband. See? That wasn't so hard.