Are you seriously recommending spending $300 on this headset? Including a USB isoloator/Schiit Wyrd??
Christ.
Since the OP has apparently established that they need to buy "something", I recommend starting with the Schiit Magni 2. No DAC, no USB decrapifier, no magic rocks. I guarantee that the Schiit amp alone will be better than any soundcard from Asus, which is not a real audio company, although they sure make a lot of noise pretending.
Then, if you want to do a serious upgrade in the future, get a better headphone and separate mic. Putting money anywhere but the transducer at this budget level (sub $300) is basically a great way to waste money.
It's a tough job to convince anyone to upgrade from on-board audio, for the very good reason that most integrated sound chips are good enough for the majority's needs. Having made the decision to upgrade, should you be looking at something a little grander?
We've used Rightmark's Audio Analyzer tool to give a top level breakdown of the card's performance. It's worth pointing out that this simply measuring variations in tones via a loopback from the speaker to the mic channel – effectively the card is listening to itself.
RMAA total harmonic distortion 24-bit/48KHz (lower is better) Intel on board: 0.131% Creative X-Fi Titanium HD: 0.0020% ASUS Xonar Xense: 0.0004% ASUS DG: 0.0027%
RMAA Dynamic range 24-bit/48KHz (higher is better) Intel on board: 90.4dBA Creative X-Fi Titanium HD: 113.2dBA ASUS Xonar Xense: 115.0dBA ASUS Xonar DG: 103.3dBA
Noise level 24-bit/48KHz (lower is better) Intel on board: -90.4 Creative X-Fi Titanium HD: -113.4dBa ASUS Xonar Xense: -116.1dBA ASUS Xonar HD: -103/4dBa
The Xonar DG gets as close to its claimed stats as any card we've tested in the Rightmark tests, which is a good start. Subjectively, it also delivers on its promise of outperforming on-board audio by a long way. The headphone amp in particular, which can be tuned for high impedance headsets up to 150ohms is an exceptionally good touch at this price.
If you game through headphones, this is well worth the upgrade, with a powerful bass blast that doesn't drown out more subtle midtones and high range effects. For this alone, we'd choose the DG over the slightly more expensive Creative X-Fi Xtreme.