[Caguioa]

so i really want to get into whoel audiofile thing and having great headphones,

i have my eyes set in in ear pair and over ear pair,

so far its sennheiser ie 800 and hd 800
and since i am mobile person im thinking of getting the
Oppo Ha-2(dac/amp)

 

[Vividcard]

So let me ask you a few questions, because this may help avoid some mistakes that others (Including myself) have made. I'm going to list them below:
 
What music do you normally listen to?
What makes you like the specific music you like.
What parts of the song do you like to feel?
Are you a Bass head? Or do you like the highs in a song? 
 
Not to pick on everything we've got so far. But I wouldn't want you to drop the level of cash that the gear listed costs only to find that the gear isn't really the right fit for you. But also, there is another important set of questions.
 
What is the quality of your MP3 collection? Have you been vigilant to only get high quality audio? If you have been purchasing music from places legally you are usually getting a pretty decent quality. If you have been taming the not so legal beasts, then that's another story. It is important to know the quality of your collection because as you get into higher quality gear you will begin to really tell the difference in the source audio quality. 
 
FLAC files are a good way to start. There are a number of perfectly legal ways to get your collection started. For me, I went to local goodwills and searched online, I purchased the CD's, ripped them as desired, then re-donated them to goodwill. I do this mainly because it is very difficult to find all the music I like on legal download FLAC sites. Good luck and hope it works out!

 

[Vividcard]

As a side note, you may want to throw this in the help/recommendations area. As it will see a larger audience and will get the responses from some of the long time audiophiles out there.

 

[adamlr]

so i really want to get into whoel audiofile thing and having great headphones,

i have my eyes set in in ear pair and over ear pair,

so far its sennheiser ie 800 and hd 800
and since i am mobile person im thinking of getting the
Oppo Ha-2(dac/amp)

 
i get the feeling this doesnt really belong in the music forum, but nonetheless...
 
Vividcard is making a good point. this is your first step into "audiophile" land. and your leaping in with top tier gear. be sure you educate yourself properly first, and make sure that the set you decide on does infact have the signature most suited to you.
 
as for file quality. thats a hell of a discussion... a "pandoras box" of sorts. youll find infinite reading material on the subject both on this forum and online in general.
to offer my personal opinion - 320 kbps mp3 is absolutely fine. the source of such files is of some importance though. so you should make sure to get the files from a source you trust. low bitrate files (mp3 or otherwise) can be "disguised" as high bitrate ones. it does seem somewhat unlikely to me, but it is very possible.
 
the most important part of good audio is good recording/producing. something you and i have no control over. great songs can be poorly produced and vise versa. no bitrate in the world can fix a bad mix. i think thats something to keep in mind aswel...
 
for a more indepth answer, and certainly more opinions, try searching the differences between "lossy" and "lossless" compression. you may even find some comments of mine around the "sound science" forum.
 
on another personal note - if you do indeed search up on the subject, you may find alot about bitdepth (as opposed to bitrate), 16 bit vs 24bit (or even 32). unless youre truly interested, id stay away from the subject. it is related, but depending on the conclusion you reach on the original subject, this other one will sort itself out on its own. i hope i havent only made things more complicated with this...