Well, folks, I've been listening to the He400 for about a week now, attempting to steep myself in their dark but sumptuous sound, and I have to say: these are some genuinely impressive headphones. At first I wasn't so thrilled with them, though; in fact, my first few listening sessions left me somewhat underwhelmed and a little sullen. I guess my expectations were unrealistically high. But crazy expectations are not the whole story here: the he400, to my ears at least, do falter a little. At first, I was only aware of the vaguest of problems, a troubling something I couldn't quite define. But then again, how could I concentrate on anything negative with the he400 seducing me with its incredible bass reproduction.
Regarding the bass, let me just say "wow!" I can't add too much more than that; the consensus view is pretty much dead-on. But there was one aspect of the bass that did, in fact, surprise me: the imaging. Many headphones, especially bass-centric headphones, blur the imaging in the bass department, but the he400, somehow, reproduces the entire gamut of bass--drums, cellos, Leonard Cohen's gravelly voice, etc.--with impeccable clarity, precision and dimensionality. I really think that these headphones (even when subjected to poorly recorded rap or pop music) are incapable of producing an amorphous thud or boom. The only other headphones in my collection capable of this sort of imaging is the HD800. (The HD800, of course, is the undisputed the champ of imaging.)
But now back to that subtle but intractable problem I mentioned earlier; it took me a good while to figure it out, but after a few days of extended listening sessions, it finally dawned on me: when it comes to the human voice, the he400's are male-centric headphones. That's to say, they'll reproduce Nick Cave's voice with startling clarity, but not PJ Harvey's. Indeed, female voices often sound veiled and sometimes even a little nasally. Once I realized this, I almost returned these headphones to the retailer. Out of sheer curiosity, however, I decided to pull out my old Behringer 10 band graphic equalizer. Equalizers, I know, are generally frowned upon; moreover, I've never satisfactorily eq'd any of my headphones before. Such fiddling usually injects an artificial something into the sound, so as a rule, I don't use eqs. But a modest 3db boost between 1khz and 6khz worked magic with the he400. I'm not kidding. Now, with the help of Lisa Gerrard, these headphones are singing angelically to me. I am very happy indeed.