I've had D7000 and i've currently got D2000 and HE-5LE.
Both D2000 and D7000 have exceptional bass, not particularly bass heavy but the quality of the bass is excellent, they do however suffer with slightly recessed mids (More so the D7000) and i find the treble a tad veiled (more so the D2000) compared to the HE5-LE.
The HE-5LE is no bass monster, it reproduces bass with deadly accuracy but doesn't have the quantity of the Denon's, but it excels with the mids and highs, they are sparkly but not over bright, deffinately no sibilance to my ears, and they are crystal clear sounding.
For what you're after the D2000 + D7000 are fine cans, the D7000 being more refined and (alot) more expensive, both need only minimal amping.
If you can afford a good amp then i'd recommend the HE-5LE too if you can forgive the lack of bass quantity.
I've not personally tried a HE-500, but they're esaier to drive than the HE-5LE and are (according to others) a more refined sound, they would need more amping than a Denon, but not nearly as much as the HE-5LE.