[fmmirel]

Hi all,
 
This is actually my first post here. Awesome forum, with lots of knowledgeable people. I'm in a bit of a dillema, and I hope someone more experienced with headphones can help.
 
I currently own a pair of HD201s from Sennheiser. The problem is that, even if it sounds somewhat decent, when I bought them, I could not help but feel a sense of disappointment that I did not invest slightly more money for a better pair of headphones , even if I'm on a budget. 
 
I used them at the office and a colleague of mine has the HD515s which sound a lot better. I've read a lot of the threads here and I really didn't see anyone raving about the HD515s and this makes me wonder how much better can the headphones you talk about sound I guess the answer is, a lot better.
 
After some research. I narrowed my options a bit but I'm still not exactly sure what to buy.
 
What I look for:

• Open back. It's not a show stopper feature for me but it would be nice to have.
• I would also like the headphones to be comfortable and pretty well built. Big cups with velur pads are a plus.
• Also a huge huge criteria for me is durability. I would be willing to sacrifice a bit of the sound quality just to get a durable, lasting pair of headphones. I don't plan on bashing them on the walls but I'd like a pair of headphones that can withstand the test of time (good cabling, decent plastic that doesn't crack from an occasional drop).
• Don't plan on doing much gaming with them. Perhaps some slight movie watching. My main usage would be music listening. I have a pretty large collection of lossless audio files. I listen to a lot of genres but I'm very partial to metal. Even so, I would like to have good allrounders for most of the genres. 

 
 
Budget: 150 $ the absolute maximum limit . Would actually prefer something around the 100$ mark.
 
3 options that I'm considering are:
 
Superlux HD-668B
Good Points:

• fits closer to my actual budget and I found them at a local store lower than the amazon price. (huge +)
• 3 year warranty in case they break. (huge +)
• semi open back design
• detachable cable

Bad Points:

• dodgy build quality (this point is kind of unclear to me, they may actually be good)
• somewhat uncomfortable (at least that's the conclusion I reached after seeing some reviews)

 
Audio Technica M50s
Good points:

• everybody praises them for music audition (big +)
• great build quality (big +)

Bad Points:

• will have to wait a couple of months to get these, I have to wait for a friend to come back from the US with these. Local stores in my area are charging ridiculous amounts for cash for these compared to the Amazon price.  Downside is the fact that I have to wait a lot for them and I can not rely on any warranty. (big -)
• closed back
• bad soundstage
• they stretch towards the top of my budget

 
Audio Technica AD700
Good points:

• open back
• comfortable (great +)
• good build quality
• great soundstage (people say soundstage is not important for music but I still think it's nice to have, am I wrong?)

Bad points:

• Must also be ordered from the US. So long time to wait for them and no warranty. (big -)
• From what I hear they are more appropriate for games and movies and not for music.
• Really weak bass

 
I've also looked at other alternatives like the Grado 80i but many people complain about their build quality and they seem really uncomfortable. I would prefer headphones with large cups like the ones from the AD700. Actually AD700 looks like an awesome pair of headphones that comes really close to what I look for but that underpowered bass really keeps me from buying them.
 
I know that many people praise the Superlux HD-668B but I'm afraid of making the same mistake I made with the HD201: buy them, and then regret not investing more. Is there a really noticeable difference in quality between the two? The same question goes for Superlux HD-668B vs the two Audio Technica options Any other recommendations considering the criteria I just mentioned?
 
I'd like to get something that would keep me from investing money again for a couple of years so if it's really worth it I may go slightly over my budget. I don't really want refurbished or second hand earphones since I want them to last a while.
 
Sorry if I made any spelling mistakes, english is not my main language. Also sorry for the lengthy post
Thank you!