[RagunaAsh]

 
The Mad Dogs look like excellent headphones, but I don't think they are a good choice for using with no amp as the OP will. Correct me if I'm wrong though. 

Fiio E07K and E10 are the go-to recommendations for inexpensive DAC/amp combo units, but IDK how well either would work with the Mad Dogs. 

True. I think, like a lot of headphones, it's better to say that they scale VERY well with an amp. But as a first venture into this, it might be better to go with a different set of headphones, or maybe $200 'phones + $100 amp > $300 'phones.

 

[MultiverseAFK]

I've decided to get the Audio Technica A900X. After you guys told me how much open cans leaked, I figured that for a first set of higher end headphones, closed should be fine. I also don't think I'll need an amp, since according to this buying guide (http://www.head-fi.org/a/buying-guide-headphones-by-price-range) the AD900s, which are just open versions of the previous model, do not need an amp.
Of course, if I'm wrong please tell me, since I have zero experience. I've also been told that I may need a DAC. I have a Macbook, so are there any recommendations for better music players on the mac and relatively cheap starter DACs that I could use?

 

[manbear]

DAC and amp go hand in hand. A DAC converts the digital files to music, and an amp makes that music loud enough for you to hear it on headphones. You can't plug headphones into a DAC by itself. 

IMO you just use the macbook by itself, but if you want something more, look at the Fiio E10 or E07K. These are DAC/amp combo units. You plug them into your computer via usb, then plug your headphones into the Fiio. 

 

[MultiverseAFK]

The A900X just game arrived in beautiful packaging. Thanks a lot for helping me get into the higher end audio world guys! I'll remember to try those amps you guys suggested, and I know I can rely on Head Fi for experienced audio knowledge.