I am curious as to other people's experiences with the Sennheiser HD 400 Line of headphones (HD 419, HD 429, HD 439, HD 448, HD 449) in regards to build quality. I personally own the Sennheiser HD 439's, and while they are primarily built out of plastic I believe that they are actually built pretty well. Has anyone had issues with their Sennheiser HD 400 series headphones breaking prematurely? So many online reviewers state that they feel like the HD 400 series headphones are prone to breaking and aren't built very well. I beg to differ. What is your guys experience?