Nathan Edwards Jul 01, 2008

Asus Xonar D2X

At A Glance


The EAX 5 hack is commendable and the cards LED lights add flash.

Pan Flute

Initially spotty PCI-E support that must be fixed with a BIOS update.

Much hay has been made of the incredible speed advantages PCI Express offers over PCI. Beyond GPUs, however, we haven’t found much worthy of occupying those slots. Asus hopes to change that with its Xonar D2X card—the first soundcard we’ve reviewed that makes use of the PCI Express interface. The D2X is basically a PCI-E version of the Xonar D2 (reviewed April 2008). In our review of the Xonar D2 we lamented the card’s lack of advanced EAX support—EAX 3 and above are proprietary to X-Fi-chipped soundcards, making those cards the obvious choice for gamers who want the best audio quality.

Or maybe not. With the Xonar D2X, Asus has done an end run to get a level of advanced EAX support in the card—but it’s not without controversy. The D2X instructs games that it has EAX 5, and the card’s drivers then shunt the EAX calls into its own effects engine. The results are far from perfect. Using EAX compliance tools, we found that the drivers didn’t support many EAX functions, such as reverb and filtering. Asus even admits to this. But the hack at least gives the card access to some functions that were previously locked up, such as support for additional audio streams in Battlefield 2—one of the handful of EAX games even available.

We’re more troubled by this card’s PCI Express support. Our D2X simply wouldn’t work on two different EVGA 680i SLI motherboards, and users have reported issues with nForce 790i boards as well. Asus tells us the problems are related to a BIOS issue that is being corrected by board vendors. Nvidia confirmed that it is working on a BIOS update that should be out by the time you read this. The D2X worked fine on Intel P35, AMD 790FX, and MSI nForce 750i boards.

The Xonar D2X uses the same audio codecs and offers the same I/O ports and Dolby Digital Live support as the D2. The D2X, however, requires a floppy connector for power.

In game frame rates, the PCI Xonar D2 was slightly faster than the D2X. We surmise this is due to superior drivers for the D2 or the PCI-to-PCI-E bridge chip on the D2X. Either way, the differences are minimal, and frankly, frame rates should no longer be the primary factor in soundcard decisions. Far more important is audio quality and gaming API support. In these areas, the Xonar D2X does well. The audio quality, rated at 118dB, is quite good, with no transient audio ghosts. The Auzentech X-Fi Prelude (reviewed April 2008) edges the D2X in our 24-bit/96KHz audio-file listening test, but honestly, both cards sound great and far exceed onboard audio.

So what would we buy? It depends. The advanced EAX in the Xonar is flawed, but it sorta works. If you want a full EAX 5 card, you have to go X-Fi. But that limits you to PCI, as the PCI-E version of the X-Fi lacks advanced EAX support. That makes the Xonar D2X the most feature-rich PCI-E card today, and that’s not a bad place to be—even if the EAX is faked.


Asus Xonar D2X

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