Reply to Bought Pioneer HDJ-2000's, are they right for me?

Bought these on the back of hearing good things about them from my brother's friend (who's a DJ) and from the reviews I'd read online, but now beginning to believe I may have jumped the gun a bit...

While I've always been interested in DJing and intend to eventually get into it once I have the time and gear , initially I'll be using the headphones for casual listening, be it while studying, at home, travelling etc. Rather stupidly I didn't really research how appropriate they are for this kind of use before I bought them, and from what I've read since they're not ideal for use with an iPhone or other portable devices as they don't possess the necessary power. Is this indeed the case? Would I need an amp in order to get the best out of them?

Basically I bought them through the excitement of finally finding a store which sold them and the fact they're regarded as top of the range, yet now I'm left wondering whether I shouldn't have dived in and rather looked for something more appropriate and less pricey. The Sennheiser HD 25's obviously have a great reputation and are a fair bit cheaper, while I've noticed the Pioneer HDJ-500's have got great reviews and are cheaper still, would these be better options for me at the current time?

Any thoughts would be much appreciated.