They have defective speakers. I have owned mine for two years and the speakers have blown twice. First time the replaced the amp, now they will not help because the speakers have a 1 year warranty. I have never had this thing past 5. The rep I spoke with said it is not defective or they would have a file on it being a recurring problem. A quick search brings up a different response with tons of people stuck in the same boat. Now it is my personal mission to make sure nobody makes the same mistake I have. Hope this saves at least a few people some time and money. Thanks.
Hartke says that you MUST BE CAREFULL with the 30 or 50 HZ control on their graphic EQ, cos' it can results in severe damage for speakers.