I went ahead and got the 558s. They're much better that the K240s. Thanks for your help guys!

Would getting a soundcard fill in for getting a DAC/amp? Or would I still benefit from getting both?   Soundcard would be something like this: http://www.amazon.com/ASUS-XONAR-Headphone-Audio-Card/dp/B0045JHJSS/ref=sr_1_1?ie=UTF8&qid=1398320126&sr=8-1&keywords=asus+xonar   And it sounds like...

I'm for a headphone that will fill my needs properly with making as as few compromises as possible.   These will be used for mostly gaming and listening to music.   Budget - Under $150. If there is a pair that's leaps and bounds better for not much more I will stretch for it.   Source - PC...