obsidyen
Headphoneus Supremus
If the HD 800 S is used on a good system, I don't see the point of owning both the HD 650 and the HD 800 S. The HD 650 doesn't really address any weakness of the HD 800 S that well.
I think a planar headphone (with a good planar bass) makes more sense to compliment the HD 800 S with rather than the HD 650.
I agree with the first sentence. I really dislike planar sound though. Planar headphones sound boring and lifeless to me. If I were him, I'd buy Fostex TH-610 as a 2nd headphone. It's closed back and has superb low end. It would complement HD800 S well.