[atomiccow]

Never heard of this happening before. As in, if you put the cans down on a flat surface, they physically rattle against the surface? That's some bass!

 

[duncan1]

Squallkiercosa has a point I came   across that fault  many times when high distortion was measured on my equipment.mainly at a higher  frequency producing a "buzz" vibration.
            If other people complain  of those particular headphones as well then it would be a resonant frequency of the design.
              Or the amp has an uneven FR. as a result of a fault.