[cyberidd]

If it only happens at unsafe levels, just avoid listening that loud and replace them later if they actually do go.

 

[BushGuy]

It sound that, in all likelihood - it's a case of clipping (cause - insufficient power is being supplied an you need a decent amp). Reproducing good bass requires the most power needed by headphones, and the louder you play your music - the more power you will need. Doubtless, you are hearing it only on the left side - because most recordings are setup with bass player on the left, and only a residual portion is picked up for the right side.

 

[MrFeature]

I have two pairs of DT770s that both exhibited the same buzzing sound in the left ear. I took apart one pair and discovered that the brass retaining clip on the right-channel wire could be vibrating against the cup. I tacked it down with a minimal amount of hot-glue and it seemed to solve the problem.

I applied this solution to the other pair and it too solved the problem. This has lead me to conclude that the buzzing is the sound of minute vibrations of the brass retaining clip on the right-channel wire.

Here is a photo of the brass retaining clip: