An open headphone like the HD 600 (which I'm wearing now) is really unfair to compare against noise canceling; I use Beyerdynamic DT770 for "closed", and in-ear from etymotics or ultimateears, rather than active noise canceling -- the only active noise canceling headphones I have are Pro Ears and MSA Saladin (shooting/military ear protectors which take radio input).

I'd be upset if my home environment were loud enough to warrant noise canceling, though.