Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Worthless

This my third set of headphones from Sennheiser in the PMX-70/80 line. They have all failed in the same way - loose connection at the headphone jack. After 2 months, this set is dead. I'm returning it under warranty, but I'm going to start looking for another brand. Strongly recommend you do the same.Update: Sennheiser denied the warranty claim because the headphones were not purchased from an authorized reseller. Be warned or stay away!