How does each set compare? I know the HD is a step above the EF, but by what margin? I have the EF in my possession but I might upgrade to the HD, havent heard it yet. One of the reasons is my amp is 180 watts X 2. Seems like the HD will handle the power a lot better, but it's a bit more money. Is it worth the upgrade or should I just run 180 to my EF's?