[Sonic Atrocity]

Alright, I am on the market for some headphones. My budget is between $300-$500 dollars (I am willing to spend this on the cans alone. Therefore, I am willing to spend more money on additional equipment for the headphones). I realize that once I spend that much I may as well invest in better equipment (ie: headphone amps). What I am looking for are headphones that I can walk around with. Additionally, I am looking for passive noise cancelling headphones that are very effective (without sacrificing sound quality). Although, I recognize that with my budget I plugging my headphones into a digital music player (which I am also on the market for) wouldn't quite cut it. But, I am wondering if it will still sound great. Additionally, I plan on getting an amp for listening at home (but that won't be until the future). 
 
What I am also looking for is a digital music player (I figured I'd throw that into this thread and just keep it all together

) that will give me the best sound quality (using lossless ALAC's of course) and has an on-board equalizer (which I plan on learning to use effectively). Is there a difference in sound quality between lower-end headphones and higher-end headphones when plugged into a digital music player? Also, if anyone has any amp suggestions (along with a basic description of what my options are... I am doing my own research but I find that a lot of people here are very receptive and offer great answers) that'd be great, too. 
 
I usually listen to a lot of metal, industrial, and rock but I am also looking to get into more classical, jazz, and any other genre. But, I think that I may want a pair more geared towards the metal and industrial

 but not so geared towards those two genres that listening to other genres is a lacking experience. I want a good pair of headphones that are great all around. I don't want to sacrifice the quality of my higher, lower, or middle range frequencies. If you want some examples of what I listen to check these out (mind the crappy sound quality. It's on youtube and some of the people put crummy rips on there). 
 
http://www.youtube.com/watch?v=rkrjE4QRsys
 
http://www.youtube.com/watch?v=aFqN7gEx5yw
 
http://www.youtube.com/watch?v=5o4YJsPWfvY
 
http://www.youtube.com/watch?v=XtP_HnZgVGw
 
http://www.youtube.com/watch?v=IaN3YEbYbng
 
Anyways, I appreciate you guys taking the time to check out my thread. Everyone here has been really helpful and very informative! I look forward to your responses.
 

 
edit: I was just looking around... do people walk around using portable headphone amps? Would that be a practical idea? I was thinking I could plug my cans into an amp in my backpack and walk around.

 

[Sophonax]

Your preference for rock and metal music probably points to Grado headphones.  Unfortunately, these are open headphones and don't do anything to cancel out exterior noise, but they probably would give you the most bang-for-your-buck with those music genres.  There are a few models in your price range:
 
SR325i (or the Alessandro MS-2i)
RS-2i
HF-2
 
The SR325i are typically described as having more treble energy, whereas the HF-2 are on the other end of the spectrum with a bassier, more treble-neutral offering.
 
Also, with reasonably high sensitivity and low impedances, Grados tend to work pretty well straight out of a DAP.  They also scale reasonably well -- if you do get a good amplifier, you will notice an improvement in sound quality.
 
If you really need something that will block out exterior noise, I would probably go with a pair of Ultrasones.  Maybe one of the following:
 
HFi-780
PRO 750
PRO 900
 
These perform pretty well with rock and metal as well, though probably not as good as the Grados.  Also like the Grados, they sound pretty good straight out of a DAP but again will improve with good amplification.
 
It seems that a portable amp may be an option for you as well, so that you could use it at home, or on the go if you wanted.  Just to get you started, Ray Samuels Audio offers quite a few different portable amps that typically garner good reviews.  Other makers of portable amps include Headamp, Headstage, ALO, and TTVJ.
 
As for DAP recommendations, I can't really help you there...

 

[Sonic Atrocity]

Thank you for the information! I will definitely post back with a more in depth response.