What PurpleAngel asked, plus:
Are you OK with open cans (they leak sound)?
What is the format of your music and other sounds you will putting into these cans?
Describe the sound signature that you are seeking? If you don't know (and even if you do), what genres of music do you plan to run through these cans the most?
Do you plan to use them outside your home? If so, in what way & with what equipment?