Does that include speaker stands (or the speaker/floor interface)?

Surely some changes are bleedin' obvious and even the most fervent objectivist wouldn't need a BT or DBT to tell which he preferred.

Let's say we put a 'black box' into the circuit that added varying amounts of high order harmonic distortion to the sound coming out of the speakers.

We can all imagine then, that when the distortion setting was set to 'very high', the difference would be clear to everyone. You could also reduce the distortion until it was so low that a BT would be required for anyone to be able to consistently give an accurate comparison between on and off.

So are we talking about a question of sensitivity here?