I don't have the resistors and have never heard them used, but from what I understand from these forums, they are used to take the edge off of the tweeters. Just rub them around the outer perimeter of the twee...oh, wait.

They limit the high end output to make the speakers seem less bright. They are inserted in between the tweeter and the wire from the woofers/midrange. Some people like them, others don't. Same as everything else...

I am the Doctor, and THIS... is my SPOON!