HE-400 are full-fledged planar magnetics. There's no getting around that.
I don't think HD650 needs all that much to drive, but the HD650 crowd loves to use the most expensive amps they can find so their hd650s can sound marginally and marginally better. Just because an amp sounds a tad better doesn't mean there's a difference between properly driving the headphone or not. Likewise HE-400 can get a decent volume out of an iPod, but not for high dynamic range songs.
And he's right, that page was last updated September '11. Linking it is ridiculous.
Edited by TMRaven - 5/29/12 at 4:30pm