Last year I got Sennheiser HD419's and they sounded amazing but a little muffled, like they were holding back the mids and trebles. Now, I've decided to get professional headphones, and I've settled on either the V6's or the 7506's.   What's the difference between these two headphones besides...

Is this some kind of special version? A studio variant with even more neutral sound? A regular HD 201 with smaller earpads? What does the S stand for? "HD 201S" is printed into the plastic of the headphones where the normal "HD 201" would be