ProtegeManiac
Headphoneus Supremus
I am not sure what this means
He meant that if there is enough variance in the distance between your ears and the tweeters vs the midwoofers, you'll hear the sound of one set before you hear the other. Combined with reflections that can cause imaging issues as well as sibilance - the latter isn't always the result of a peak in the 4hz to 8khz region but in some cases because your hear the same note, with sounds coming from both tweeters and midwoofers, one before the other. In cars since this is the default reality considering tweeters aren't mounted near the midwoofers and most people don't drive a Maclaren F1, processors and receivers usually come with some kind of DSP that can introduce a delay to nearer speakers.
Here are a couple of quick illustrations I did for an older thread regarding active monitors sitting on the desk vs one on an elevated stand (top), note how there is a distance variance easily seen on the lines; in some speakers, although almost exclusively passive speakers, the front baffle is angled upwards (bottom) which helps raise the soundstage to eye level (even in non-nearfield set-ups, in case your stands are too short), but ultimately it helps reduce the variance in the distance between the tweeter and woofer from your ears.