Second report on the K400: this headphone is a pure joy to listen to, especially orchestral music. The sound stage is wide and deep, detail retrieval good, dynamics amazing and frequency response quite even. I haven't enjoyed a pair of headphones this much for quite some time.
However, I have one major problem. At certain loud moments - full orchestra with heavy bass - there is a loud rattling noise in the right channel. I've checked the driver for hairs etc but the surface is clean. I've also opened the back and couldn't find anything visually or mechanically wrong with the driver assembly. This is the driver type with the blue "blob" fixing the voice coil wire to the inside of the diaphragm - could this be resonating against the membrane? I have a vague memory of reading about this somewhere.
Any light shed on the matter would be appreciated.
Still, when the rattle is non-present the music presents itself in a most persuasive manner...