ClieOS - How would you compare this to the TDK IE800? I may be looking to replace the IE800 because the marginal build quality and isolation mean that I don't use it as much as I would something with better build quality and isolation. SQ wise I'm very pleased with the IE800. My one totally subjective complaint is that its a bit to airy for my taste - I don't hear the thickness of notes or analog-ness that make the instruments sound real to my ears. Would the RE400s be a good substitute?