Asus' Xonar D2X
PCI Express audio at last

With its fingers in just about every PC component category, it was only a matter of time before Asus entered the sound card market. They're diving right in with the Xonar, too. Not only does the card target the high end of the desktop sound card market—prime X-Fi territory—but it's also available in both PCI and PCI Express flavors. We'll be concentrating on the PCIe Xonar D2X today, but apart from its interface, the PCI-based Xonar D2 is all but identical.

As one might expect from a high-end sound card, the D2X isn't cheap. It's currently selling for $190 online, which is roughly double the cost of Creative's cheapest X-Fi. However, that price tag also puts the Xonar within $10 of Auzentech's X-Fi Prelude.

The card itself is dominated by an EMI shield designed to reduce interference within the relatively noisy confines of a modern PC. With a subtle speaker motif, it doesn't look half bad, either. The EMI shield effectively hides most of the card's components, so there isn't much to see from here apart from a PCI Express x1 connector and a four-pin floppy power port. The presence of an auxiliary power connector is a little worrying, so we'll be looking at power consumption a little later in this review.

To get a closer look at the Xonar, we have to remove the EMI shield. Fortunately, all it takes is a screwdriver, and the payoff is well worth it.

Naked, the Xonar gives up a bounty of onboard components and a better view of the card's internal connectors. Three are provided, one each for CD and auxiliary inputs, and another for the card's external MIDI bracket. Don't pay too much attention to the orange semi-circular bits on the card—they're just diffusers for some onboard LED ground effects.

Interestingly, the card's audio chip is identified as an Asus AV200 HD Audio Processing Unit. Ignore the name, though. Asus tells us that the AV200 is simply a modified version of C-Media's Oxygen HD, which is otherwise known as the CMI8788. C-Media has apparently tweaked the chip just for Asus to provide better sound quality. The AV200's general feature set remains identical to that of the Oxygen HD.

Between the AV200 and the Xonar's analog output ports sits a set of four TI Burr-Brown PCM1796 DACs—one for each output channel. The DACs can handle 24-bit audio at up to 192kHz and carry a signal-to-noise rating of 123dB. On the analog-to-digital conversion front, the Xonar employs a Cirrus Logic CS5381 that also supports 24-bit/192kHz audio, this time with a 120dB SNR. Overall, Asus rates the Xonar's signal-to-noise ratio at 118dB.

Continuing our tour through the Xonar's assortment of component goodness, we have the chip's TI R4580I operational amplifiers. The card also includes a National Semiconductor LM4562 OPAMP for the front-channel output.

Since the Xonar's Oxygen HD AV200 audio processor lacks a native PCI Express interface, Asus uses a PLX PEX8111 bridge chip to provide PCIe connectivity. Bridging may not be as elegant as a native implementation, but we've seen bridge chips used successfully in graphics cards and hard drives with no ill effects, so there's nothing to worry about here. Obviously, the PLX chip won't be present on PCI versions of the Xonar.

Around back, Asus peppers the Xonar's gold grill with an assortment of ports, including analog front, center, side, and rear channel outputs and microphone and line inputs. You also get coaxial digital S/PDIF input and output ports. And there's more.

Asus pimps the port cluster with multicolored LEDs that backlight each port with the appropriate color. The result is an almost unholy combination of gangsta and geek that marries the gaudiest trends associated with each. At first, I was tempted to write off the bling as another useless cosmetic treatment. However, after having to contort myself awkwardly among the dust bunnies and a tangled web of cables under my desk to connect speakers to a sound card because I couldn't see which ports were which from above, the Xonar's back-lit ports started to make a lot of sense. There's no need to worry about the piercing radiance of LEDs, either. Since the port cluster resides at the rear of the system, the LEDs only end up giving off a gentle, unobtrusive glow.

Finished with the Xonar's hardware, we're left to dig around in the box, where there's actually plenty to find. Asus bundles loads of goodies with the card, including a whopping four 3.5mm-to-RCA cables—one for each of the card's output channels. Also included is a TOS-Link S/PDIF cable and an external MIDI bracket with all the necessary connectors.

As if the array of cables weren't enough, Asus also throws in a number of software titles, including a music conversion utility that can convert tracks for playback with Dolby Headphone or Virtual Speaker, Ableton Live 6 Lite, PowerDVD 7.0, and a Cakewalk package that includes limited versions of SONAR, Dimension, and Project 5.