Thanks for all the replies! I've been looking around and it seems that it will be difficult to find a reliable amp to drive these cans for a reasonable price. So, I'm wondering if there are any other headphones out there that are good for mixing (key word "mixing").
The reason I was attracted to the 240DFs in the first place was because they are diffuse field equalized so as to provide a recreation of listening with speakers. However, I read an article (from headwize.com, I think) stating that most headphones nowadays are diffuse field equalized. Will most newer, quality headphones provide similar results to the 240DF?
I've also read some things about various software/hardware virtualizers. Any opinions on whether these are worth it or not?
I don't have space for monitors so I really need the most accurate listening experience through headphones. Ideally, I'd spend about $200 on headphones, preferably not having to buy a dedicated amp. The Sennheiser 580s are looking good to me, but I'm open to anything. Thanks again!