All that matters is what you hear, and if you're happy with what you hear. I believe that all speakers, and most audio components, exhibit some sort of physical / eletrical / mechanical break-in that is audible. Typically 30-50 hours. Sometimes it can be much longer.
These theoretical arguments have no value to anyone's musical enjoyment. My only advice is this: if you get a new component, particularly new speakers, and notice a shrillness or lack of bass, give it some time before deciding to send it back. You may or may not notice an easing of some of the annoying sonic features. Aside from that, just enjoy the music.
-Cooper
