http://www.amazon.com/Sennheiser-Headphones-Burl-Wood-Accents/dp/B0042A8CW2/ref=sr_1_1?ie=UTF8&qid=1382850047&sr=8-1&keywords=hd598
Vs
http://www.amazon.com/V-MODA-Crossfade-Over-Ear-Noise-Isolating-Headphone/dp/B00A39PPCG/ref=sr_1_1?ie=UTF8&qid=1382850150&sr=8-1&keywords=M100
With a budget of 300 or so, you can get the HD598, you would have enough for a FiiO E17. With the M100 you have all sorts of cool stuff like the case and the extra cables but not enoug for an amp.
Or you could just go straight to this one:
http://www.amazon.com/Sennheiser-Dynamic-Professional-Stereo-Headphones/dp/B00004SY4H/ref=sr_1_1?ie=UTF8&qid=1382850280&sr=8-1&keywords=Hd600
Other experienced headfiers say they would choose the 600 unamped over the 598 amped. I have no experienced with the 600 unfortunately. Then of course, if you go that route, it wont be long before you get into the amplification game.
The senns will perform well for home use, not so well for outdoors. The m100, will of course be better for mobile use. The M80s are built like tanks, and so is the m100 having the same lineage. I can tell you from experience, the 598 will not survive long term on road use.