Ariel - Sounds to me like it could be a blown driver or just a hair from your head has snuck into the housing and is resting on the membrane of the driver. If the former, you need to send it back to Grado, if the latter, you can probably remove it yourself. Do a search at Head-Fi and see if there are some threads about buzzing in Grados, then ask/post if you don't find an answer. Good luck.