My youngest has a pair of AKG k240 MkII headphones, and he came to me and said the sound started to go funny. Sure enough, when I tried them, part of the audio sounds muffled/distorted like it's underwater. There's no obvious signs of damage to the headphones so I got another cable. Same problem. I sent that back and bought a different cable - problem persists. If I pull the plug out 2 to 3 mm it sounds fine, but it's literally sitting so loose in the jack that the weight of the cable alone can pull it free. The original cable is the same. I'm confused - any ideas?