I ran through this article this weekend, and while it is long, it is very very in depth and helps you get all of the ins and outs of impedance and how it can effect your studio and also expands on the voltage matching conversation as well, which according to the article is much more important these days.
If you love understanding every aspect of your studio and don't mind a little extra electrical engineering knowledge, you'll love this article.
http://www.soundonsound.com/sos/jan03/articles/impedanceworkshop.aspLet me know what you think.
