Sennheiser HD 660s problem


I just got a pair of Sennheiser HD660s and  right from the box they do not  reproduce midrange frequencies , voices are barely heard in the background , connections were doble checked and different sources used .   I called amazon and they agree for a complete refund, excelente service by the way . 
I ask a technician and He told me they are impossible to repair , that probably came defective from fabric, and it is impossible to get replacement drivers.  I am against the current trend that everything is disposable .  Any ideas or suggestion.  I probably will order  Focal or audile headphone , Sennheiser is not an example of German engineer anymore. 

vinylnostalgic
I sent in my Sen.650's to Sennheiser for repair....came back fixed.
ELBEBE1000   In my case I disassembled the headphones and found a loose connection  , a  good technician did the solder iron  and they are working well.