Having just recently gotten my HE-5LE, I was stunned pretty much from the get-go by their realism. There's been some comparisons with the K702 in this thread, so let's start there.
Obviously they're going to be more refined, that's no question. They better be given the price difference. But what probably struck me most was the tonal balance. They're pretty neutral, but with a fullness and richness to the sound that I feel closely resembles reality, and greatly separates them from any cold and sterile sound that often gets characterized as neutral, such as with the K702. I did not find the K702 more resolving. If anything, the HE-5LE is able to better articulate both quiet and loud sounds equally well, so the faintest details in the background come through clear as a bell. Many people make the mistake of associating treble-happy phones as more detailed and resolving, and that simply isn't the case. On the K702, this frequency range takes the forefront, and that may be why one might call them "veiled". The simple truth is their mids are recessed compared to even the DT990 I have. Everything is pushed back into the distance, with the treble and upper midrange taking center stage, emphasizing the air and breaths of the singers and music you're listening to. It's not that the HE-5LE doesn't pick up on these, it certainly does, it just doesn't shove it in your face before everything else. The HE-5LE has much more mid presence, which aside from making them sound more forward can also appear to some to actually be less veiled than the K702, though my personal opinion is that it's simply a difference in volume. The tonal balance of the K702 makes them sound very artificial, like it's coming out of a speaker instead of striving for a lifelike quality. The HE-5LE presents music closer to how it really is, as it was recorded and mastered, while the K702 does much more projecting of its own interpretation. The HE-5LE certainly has it's own signature, and I wouldn't go straight to calling it extremely transparent. Its signature is full and smooth, liquid and a little lush. It's a very inviting sound that draws me towards them time after time just to hear them, even if I don't have a particular desire to listen to anything. To me, it's extremely seductive and addicting.
I immediately gravitated towards their sonic characteristic, and look forward to some possible subtle improvements over time as they get more use (and moreso when I get a new amp). I bought the K702 to service classical, jazz, bluegrass, and other instrumented stuff, and the HE-5LE swooped right in and took over their job. I literally have no use for the K702 anymore, and only keep them around because I want to hear how they'll improve with better equipment, but the HE-5LE sounds hands-down more realistic in quality and presentation, and is most at home in all the genres that the K702 is reputedly adept at. And they complement my DT990 really well too.
