The new Crusher wireless from Skullcandy is a great improvement on the old Skullcrushers. The most noticeable improvement is NO EXTERNAL BATTERIES which is very important because a person can spend hundreds of dollars in AA batteries in a years worth span for the old Skullcrushers. Another noticeable improvement is the power efficiency in the Sensation55 drivers, I don't know if anyone noticed but they are more sensitive with a lower resistance (15 ohms i believe) which deliver some heavy powerful bass at maximum power. The REX40 drivers are better...