I agree they don't look like 500 bucks cans at first. It takes a while before you start appreciating their build. When for instance at some point when you want to clean them you find out how easy it is to take them apart. When the pressure on your ears starts to diminish and you start to realize how incredibly comfortable they are. They are tight and don't move from their position. The earcups are deep enough that pretty much any ears can fit in. There are no pressure points on your head. It doesn't cause sweat or heat build up. They're light as a feather but when you have them on, they feel rock solid. There are no sounds coming from mechnical parts (once they've been used for a while).
The only reason I point this out is because I really feel the build quality of the 650 is severely underestimated.
As for their sound, I guess it's just a personal thing... Hopefully you'll start to appreciate them shortly. If not, then in your place, you ought to be able to get an interesting sale out of them.
In regards to the build quality, I wasn't comparing them to $25-50 headphones but much rather the quite elegant and all the more sturdy AKG K550. They're not moons apart, but they feel plasticky in comparison. The creaking will hopefully settle over time.
The guy who sold 'em to me said that he's owned and used them for quite some time, but they look and feel brand-new (clamping galore!) so I'm not sure our respective views of "quite some time" are even remotely similar.
I've heard of the so called Sennheiser "veil", but can't really say that I'm experiencing any such feat w/ these. They're not as stingy/harsh/"trebly" as the K550 but they definitely don't sound "veiled" in any way, to me at least. They do reach deeper and the lower frequencies are louder than on the K550, but feel somewhat sluggish instead.
It doesn't feel fair comparing the two though, having their design and purposes in mind. Apples and oranges...
I don't dislike 'em, but they haven't swept me away just yet
EDIT: Oh, by the way. Is it possible to use the HD600's grills(?) on these?
Edited by Frank Sauvage - 3/17/13 at 2:42pm