External Soundcard vs. Internal vs. Other

I have a Sennheiser HD598 and I'm looking to try to make it reach its potential. I do game, but I am looking to maximize music and movie audio with clarity, immersion, and surround and since I'm not too experienced with audio equipments, I'd like to ask for help.



Price range: around $100.



So far I'm looking at:



FiiO E10K USB DAC and Headphone Amplifier



OR



Sound Blaster Z PCIe



Do you have any suggestions? Thank you.

External Soundcard vs. Internal vs. Other