I just got these bad boys in the mail this afternoon, here are some quick first impressions I thought I'd share. A full review and comparison to the old HE-500 will come up later.
Comfort/Build: Comfort is substantially improved vs the HE-500. The new earpads literally melt into your cheeks. Pads are much more plush than both the original velour and pleather pads. The velour material that covers the top of the earpad feels less grainy/rough, compared to the velours that came with my HE-500.
The cable feels solid. It's terminated by a Neutrik 6.5mm plug. The new black cable has less microphonics than the original silver HE-500 and tangles a lot less easier. The HE-500 is left in the dust in terms of comfort, but, comes back in build quality. The HE-560 kind of feels like a toy in comparison to the HE-500. When you pick up the HE-500, you're greeted with reassuring weight and metal gimbals. The HE-500 just feels solid in your hands while the HE-560 is composed of plastic gimbals and is much lighter. It seems more fragile in comparison to the HE-500.
Sound impressions, what everyone really cares for.
Bass: Extends down to 20hz audibly/felt, with a roll off starting at around 25hz. Bass sounds quicker and has less of a mid bass hump vs the HE-500.
Mids: Goodbye recessed upper mids. The midrange is a lot more even, the depression around 2-3.5k is rectified, and the lower midrange is a bit less forward (though IMO the HE-500 was too forward). Vocals are more palpable on the HE-560, at least in terms of tone/realism. Some may favor how the HE-500 mids and vocals sound more lush and forward though. Timbre is more realistic, the tone of a violin/guitar/sax/etc sounds more lifelike with the help of the improved treble and more even mids.
Treble: Treble on the HE-560 is a touch airier and more extended. The peak at around 10k on the HE-500 is absent on the HE-560. I generally hear the HE-560 as having a brighter treble in most recordings, however, some songs that hit the 10k area a lot make it seem like the HE-500 is brighter but gives you the impression it's a bit grainy because of that peak. HE-560 is less forgiving of poor quality recordings than the HE-500, but, still plays them well. Unlike the HD800 and SR-202 that will absolutley reveal every tiny mistake in the recording.
Soundstage: Listening to binaural recordings gives you a larger sense of space on the HE-560. The soundstage is wider, but not so much so that you begin to feel distant/bored (Looking at you, HD800 and Stax SR-202). Depth is about the same, more listening will need to confirm that however.
Efficiency: Slightly better on the HE-560, but, both are nearly the same. My receiver has power output meters, to reach the same value at the power meter while playing a flat tone (100hz,1000hz,etc). The HE-560 needed to be turned 1 notch less on the volume pot than the HE-500.
Overall, It's kind of hard for me to say the HE-560 is necessarily better for everyone. From a tonality standpoint, others may favor favor the lush, warm, and relaxing tone of the HE-500 more. Though, it's obvious the HE-560 is better from a technical standpoint and I personally enjoy them more.
Photographs if anyone is interested: http://imgur.com/a/05WRb