He says that the first AK100 has some kind of lack of bass, and the AK100 II has powerful and impressive clear bass. Silent sounds became more audible too.
Don't care about his words if you use dynamic headphones, because in this case you should have the opposite result (bassy sound).
Unfortunately I use BA multi drivers, if not I wouldn't mind so much
Though ill be worried if my bassier type earphone and headphone like se215 and momentum gets more bassy with the MK2!