Well, if both are real, I'd suggest that you should send them back while you still can. Keep the money for a better pair of headphones then, because I do agree that you'll start noticing a difference at the $300-400 range. For example, I feel that the M50s don't have as much clarity as a pair of DT880s, not to mention a difference in comfort.
But as others have said, an amp would definitely help you get more out of your setup. My M50s sound better with my WA6 connected to my desktop, as opposed to straight out of my phone. The difference here isn't night and day, but they sound more lively and fun when properly amped. Just my two cents, YMMV.