New surround sound headset + audio card - for fps mmo

I Wish to buy a new headset and audio card to improve my gaming experience.

I play a competitive fps mmorpg, where sound is a big part of information you recive and need to react on.

There is sounds, such as when you are channeling a spell which is relatively loud. You are able to recongize which spell is being cast dependent on the sound. This is pretty easy, even with my current setup. (onboard soundcard and senheiser pc350).

Another type of sound is foodsteps, footsteps are very low volume and hard to hear. The direction from where the footsteps is comming from is also important, so u can know if someone is sneaking up on you. Therefore i need a pair of good 7.1 headphones.

I was told there is also some audio cards, that can enhance sounds and make for example the small sounds of footsteps louder. I want to be able to hear footsteps from as far away as possible.

my question is if, anyone have any audio cards and headphones they can recommend for the most optimal sound ?

my budget is max 600$