[retskrad]

Is there a way to find out what revision I have on my HE-400's?

 

[TMRaven]

Take the earpads off and look at the color of the plastic covering the drivers.  If it's white then you have a 'revision 2,' if it's sandy colored then you have a 'revision 3' that should have been recalled due to treble issues.  If it's a transparent white than you have a 'revision 4' that's supposedly fixed and sounds like the revision 2.