Despite their many similarities, the Xonar DGX and DSX are different sound cards designed for different markets. The DGX has headphone users in its sights, offering them universal surround sound with slightly hollow-sounding Dolby Headphone support. The headphone amps are a nice touch, and at $40 online, the DGX is the cheaper of the two.
Whether the Xonar DGX's emphasis on mid-range tones is a perk or a detriment may depend on your personal preference. There's something to be said for the extra kick the card gives to certain frequencies, but our blind listening tests didn't reveal a clear preference among our panel members for the tweaked acoustic profile. Some folks will no doubt prefer a sound card whose playback is free from embellishment.
The Xonar DSX doesn't pull any pre-programmed tricks, and it sounds more neutral as a result. Our listeners found the card's bass kick particularly compelling, but in some cases the thump overshadowed other elements. Overall, the DSX's output was the closest match for the pricier DX.
Of course, the DSX has unique attributes that extend beyond its acoustic characteristics. The card provides more output channels for home-theater setups and real-time encoding capabilities for folks who want to pass everything over a digital output. Picky users can customize the card's sound by swapping the front-channel op-amp, too, but there's no virtualization support for headphone users. The virtualization schemes built into Battlefield 3 and DiRT Showdown sound better to me than Dolby Headphone, so that's not necessarily a big loss.
The DSX's extras do come at a price; the card costs nine bucks more than the DGX. However, that's pocket change considering the expected lifespan of a PCI Express sound card.
The cost of upgrading to a discrete sound card is really quite minimal, especially considering the fact that both Xonars sounded better than our motherboard audio overall. Still, it's worth noting that integrated options continue to improve. The Realtek solution we tested is the best one we've heard in recent memory, and the gap between integrated audio and budget sound cards is definitely shrinking. We'd still recommend a discrete card for folks with decent speakers or headphones, though.
So, which budget Xonar gets our seal of approval? While those with a preference for vocals might want to opt for the cheaper DGX, we're inclined to push folks to spend a little more on the DSX. Our blind listening tests suggest the DSX has better overall sound quality, and that's what really matters for a sound card.