yeah I wonder if I got a fake pair or maybe a second revision myself, I really don't hear that dark sound people talk about.. I mean it's bassy and smooth, but not muddy in the mids or highs or anything. it's basically a smoother version of Piston 2.
maybe I'm deaf but what I hear is a very clean, smooth sound in my 461s. maybe you mistake the somewhat dark sennheiser sound signature for distortion? or maybe it's there. I don't know. all ears are different.
The HD461s aren't a good choice for true bassheads, even though they handle bass heavy music very well, if that makes sense. They're more of an all-rounder, with just a slight bass boost and laid-back treble.
The HD451s are supposed to be a bit bassier though.