I`m a bit worried that my Grado SR60s may be blown. At certain frequencies, the sound from the left ear is quite distorted. I`m listening to a Denon DM31. Could it be the Denon? I`ve noticed it the most on a couple of Nora Jones albums. I`m going to listen to a different source and compare, but, in the meantime, has anyone else had a similar problem? I can`t imagine that I`ve done any damage to the phones - I only have the volume turned up to 15 or 16 on the Denon, max.