Not knocking those doing the foam mods, but I feel it needs to be stated yet again how vitally important synergy is with these cans. Sure they can sound very good with minimum consideration to components in a setup, but it's quite apparent to me how responsive the HD650 is to changes and what's heard is the sum of the parts before the cans. I've heard my HD650 sound thin, hollow, metallic, etched, clinical, as well slow, muddy, smeared and somewhat veiled. I feel I've gone the spectrum with these cans and it's all been a result of the various configuration options in my setup. This tells me that the common complaints aren't inherent in the HD650.
Those familiar with my gear may scratch their heads at the warm signature that's apparent at every step (from dac output stage, to tubes in the amp, to the cable). Based on Head-Fi mythology, I should be hearing the slowest, most veiled and muddy signature known to man. Instead I scratch my head at the authority and slam, the width and layering of the soundstage, the energetic but smooth midrange, the dynamics and musicality, and the lack of the dreaded veil to stifle what I'm hearing.