It is sometimes possible that the transducer system of the headphones is damaged.
However, it is much more often the case that this effect is caused by hairs being stuck in the foam disk inside the ear cushion and sticking out close to the diaphragm of the loudspeaker. At very high levels and/or at very low frequencies, the diaphragm vibrates significantly more strongly and can then touch these hairs, which results in distorted playback.
To resolve this problem, it is usually sufficient to examine the foam disc of the headphones and to remove any hairs that are sticking out.
If the same problems persist, please contact our service department.