Headphone Buzz

[Burt]

I just acquired my new Beyerdynamic DT770 Pro headphones to discover that the right 'speaker' has a very noticeable buzz when playing bass. Is this a known problem with a solution, or am I gonna have to replace them?

 

[Burt]

After a bit of investigation I can't seem to hear the same buzz when using them with my hifi or directly from the soundcard (had them connected to a headphone port on my monitor).

However, the soundcard isn't powerful enough to let me increase the volume very high so it's difficult to be certain that's not it. Is it possible that whatever amp is inside the monitor (it has integrated speakers) is distorting the signal to the right channel only? The monitor speakers don't seem to have any such problem.