Mdr z7 question

[Rgbnoscopez]

I have a question and I don't know if it's a dumb question or not, ok so I have a pair of headphones (Sony mdr-z7) and I was listening to bass boosted music at a very decent volume. With the headphones on I hear zero distortion at all like it's clear as hell and there litterally shaking my head but if I take them off while playing they start crackling (even though the driver is barely moving at all) my question is, is this because of the headphones being stressed to there limits or is this simply Causes by driver movement being exposed to open air.. Other wise like I said when on (or when I put my hands on the pads ( cover whole pad and driver) there is no crackling. So do I need to be worried?

 

[RazerZ]

[video="https://www.youtube.com/watch?v=mgCAWGNjZEk"][/video]

They are defective and it appears to be a common issue with this pair, despite being a flagship.