The Beats suck.
The Beats are designed for one thing and one thing only: to deliver the maximum amount of bass possible in a headphone. They're aimed squarely at the hip hop/rap crowd, as well.
If you only listen to rap and want as much bass as possible, then buy the Beats. You'll love them - they're just for you.
On the other hand, if you want headphones that can be used with any genre of music and were developed for a clean response across the board, but the Sennheisers. Or AKGs, Grados, Denons, Beyerdynamics, Audio-Technicas, Sonys, Ultrasones, Staxes, or probably a few others I'm leaving out. But that doesn't include Bose, which also sucks, but for different reasons I won't get into. There are plenty of threads here detailing just how awful Bose is if you want to read them.
Amplification? Don't worry about that. An old two channel receiver with a headphone jack will power pretty much all of the headphones you read about here. So will the PreSonus HP4, which goes for about $100. So don't worry about an amp. There are a number of inexpensive options that work fine. You can, of course, spend a bit more on an amp if you want.
If you'd like a good pair of headphones, tell us how much you plan to spend, what kind of music you listen to, whether you'd prefer open or closed headphones, and whether you want ones that go around you ear or sit on your ear. If we know those, you'll get good recommendations.
If you want reassurance about how bad the Beats are, run a few searches for them in the member lists. I think there are something like 100,000 members now - you will find very few members who own them. Keep in mind that there are a number of people here with five or six figures invested into their stereos. They'll buy anything they enjoy, but virtually none own these. There are, however, people with huge investments into amps, CD players, turntables, etc. who own the HD-650. That should tell you something.
