Headphone novice in search for gaming/music headphones ~$150

Hi head-fi,

I currently posses a pair of AD700's and I absolutely love them. They are great for gaming because of the wide soundstage, and music sounds excellent on them as well. However, they leak a ton of noise, and I am going to be going to college soon, and I am sure my roommate won't like that. I am most likely going to give them to a friend and buy a new pair of headphones for myself.

I play FPS games on my PC around 70% of the time, and the other 30% is listening to music. I mainly listen to metal so good quality mids and highs is a must. A little bass wouldn't hurt either, but I don't listen to dubstep so I don't want anything overpowering.

My sound card is an X-Fi SB Titanium HD with the default Op-Amps. I use CMSS-3D for gaming, but I turn it off for music. I do not have a dedicated headphone amplifier, but I do have a fiio e5 (I doubt that would be of any use in my situation). I don't plan on buying an amplifier anytime soon.

I already have a microphone.

What would you guys recommend? One that I have been hearing a lot about are the A700's, which are apparently very similar to my AD700's except they don't leak as much noise. I have also heard a lot about Ultrasone headphones. One that I have heard a lot about is the Ultrasone Pro 550. What do you guys think of these?

I really want to avoid spending that much. I am a senior in high school so I cannot afford spending that much. I just bought an HD 6970 as well so I am nearly broke.

$150 is a strict budget, I can't spend a cent more.

However, I have asked some people on Overclock.net and a ton of people recommended the Ultrasone Pro 550's to me, and they said it fits exactly what I asked for:

- Decent amount of bass, but not overpowering

- Wide soundstage for gaming

- Very little to no sound leakage

- Portability is a plus but not required

- Good highs/mids preferred since I listen to a lot of metal

- Something that will sound good even though I don't have a dedicated amp