I have a pair of Monitor 70s that I picked up for a sweetheart deal a little over a year ago. Being in college we attached them to some junker receiver and never bothered to invest in anything decent to power them. This was all fine until a month or two ago when some rowdy partying left our speakers sounding muffled and without much to say for high tones. After they went bad I spoke briefly to someone at customer service who said it was either the tweeter or crossover that went bad. I'd bet it's a tweeter but before I start buying up parts and paying for shipping I figured I would ask if there is a way to definitively determine whether it's a tweeter or crossover problem.