It will depend on what the headphone you use. Judged the headphone you mentioned, it seems a sound card with headphone amp should be what you need.

Well…you didn’t mention any things about your friend’s PC…   These two models are both categorized as “Home Theater” as you can see from ASUS Xonar official site. Plz provide more info. about the choice. It’s difficult to give u any advice with this info.

Found another review of Titanium HD, http://www.techradar.com/reviews/pc-mac/pc-components/sound-cards/creative-x-fi-titanium-hd-712750/review Looks not bad but seems a little overpriced. Still looks and waits for more reviews.

I have ATH-PRO700 as well. However, since the impedance of ATH-PRO700 is just 36 ohms, I don't think you need Xonar Essence with headphone amp embedded which tends to drive high-impedance headphones. ....or maybe you focus on other features of these two cards??

Some posts on the Internet say ASUS Xonar Xense is a gaming audio set. But out of my curiosity, is this kind of audio set good for listening music as well? I spend almost the same time on listening music and playing games, and wondering whether this bundle is good for me?

Say no to Xtreme Audio, too! Not a fan of Creative, I really got annoyed by this series because of its terrible UI and "blasting" reinstallation. Creative is an old brand and really needs restructure or I wouldn't choose it again in he future.