It's not that clear in Marv's post that HD6x0 evolutions over the years did get rid of the Sennheiser veil('s myth ?). Maybe there are evolutions, maybe Tyll's quote explains some things :

The Sennheiser Veil and Other Issues
In a time when overly detailed headphones built by Grado, Audio Technica, and Stax pre-Omega were considered the norm among headphone enthusiasts, the HD 600 was heard as polite...too polite for ears used to the up-front treble and poor bass response of high-end cans at the time. And so the relentless damning began, gently bludgeoning the HD 600 away from it's first place position at every opportunity with the fluffy club curse: "The Sennheiser Veil."

http://www.innerfidelity.com/content/very-important-sennheiser-hd-580-hd-600-and-hd-650
English isn't my mother tongue (you've seen it, french team inside), so please don't be rude whether I haven't correctly understood Marv's statement (or not)

Ali

There's no "veil" unless you have one from the previous decade. Even then it's not a "veil".

So is the new package design a strong indicator for the new version? I want to make sure and minimize returning headphones (which I strongly dislike).

I believe you can find the answers you're looking for throughout this thread...but, in a nutshell as for how I hear the HD600 vs 650:

- HD650 has a bit more mid-bass. My HD650 has better distortion in the bass vs the HD600 I owned.
- HD600 has a bit of a 2-5KHz emphasis that may or may not bother you. It varies from person to person, and some may not hear it as being emphasized there whatsoever. HD650 in comparison smooths out this emphasis.
- HD650 is a bit darker and slightly more rolled up top, but, really, not by a whole lot.
- HD650 sounds a bit more refined to my ears in ways that are harder to explain, but it's subtle.

For me, it came down to the HD650 because I the HD600 sounded "hot" to me with that 2-5KHz emphasis.