Sys40 is the driver in 650 / 600 or in 660s? So essentially it costs 3 times more than the 660s driver or the old ones in the 650/600?To be honest that is how I feel except that I feel it's as if they took the HD580 and HD660S to make the S2 , as brought to light by Jermo K at Sennheiser the driver in the S2 is indeed the new evolution with the voice coil and membrane.
If they manage to have timbre and tonality of 58x/6xx with technicalities of 660s more bass and more treble then yes endgame for sure.