The only way phones can do damage is by playing too loud for too long. There are different design: the ones that sit on your ears, like the Grados, and the ones that cup your ears, like the Senns. Oh yeah, there are also ear buds which go in the ear canal. The only real difference that I'm aware of is comfort. With my AKGs, I can only listen to them about 2-3 hours before they start giving me a massive headache. When you buy, make sure the store will let you return them if you are not 100% satisified. Extended wearing is the only way to find out what's right for you.

Again, if phone listening is going to be your primary source of audio stimulation, you should look into a nice headphone amp. Well worth the investment.

One more thing, like when comparing loudspeakers, make sure you evaluate and equal volume levels. If not, the louder one will always sound "better."......Colin