The X1's would serve you well in BF4. Another choice would be Sony's MA-900.
A sound card isn't always required since most mother boards have on-board audio now. However, Creative's new Z series gives you a very nice surround sound experience. That Recon USB is well though of as well.
I really don't like how flimsy the Sony ones look, plus the x1s seem to be better. Should I go for the x1s over the Sennheiser 558s?
Hm, I'm thinking of going for the Asus Xonar DGX because going for a top notch sound card would be over my budget, I have a gigabyte UD3H Z77X motherboard, will I see much of a difference?