Linearity is an excellent assumption for virtually any non-overdriven modern amplifier. THD measurements make sense for speakers, but that's not getting in the way of what the author is attempting to do here.
I don't even know where to begin addressing everything that's wrong with this article, but assuming linearity isn't one of those errors.
Comments
This assumes your amp and speaker are linear systems.
Linearity is an excellent assumption for virtually any non-overdriven modern amplifier. THD measurements make sense for speakers, but that's not getting in the way of what the author is attempting to do here.
I don't even know where to begin addressing everything that's wrong with this article, but assuming linearity isn't one of those errors.