For years, we’ve trumpeted the benefits of discrete sound cards. They simply sound better than the typical integrated audio on motherboards, especially for those with discerning ears and halfway-decent speakers or headphones. Good sound cards tend to last through multiple upgrade cycles, too. They’re amazingly inexpensive considering the expected lifespan. Indeed, the two we’ll be putting under the microscope today—Asus’ Xonar DGX and DSX—sell for less than $50.

If the names look familiar, that’s because the cards are the PCI Express versions of the Xonar DG and DS. Those older models have PCI interfaces, like an awful lot of other sound cards, and PCI slots are quickly disappearing from modern motherboards. The Xonar DGX and DSX drop into any PCIe x1 slot, and those should be with us for a good, long time.

Each card has a unique character. The DGX courts headphone users with a dedicated amplifier and Dolby Headphone surround-sound virtualization. Meanwhile, the DSX offers home-theater users a replaceable op-amp, support for more output channels, and the ability to encode multichannel digital bitstreams in real-time.

How do the two compare, and more importantly, how good do they sound? We’ve conducted a mix of performance, signal quality, and blind listening tests to find out. We’ve also thrown in our favorite mid-range sound card, the Xonar DX, and a motherboard with Realtek’s latest audio codec. This should be interesting.

Moving considerably slower than the speed of sound

Before we dig into the Xonars, it’s worth taking a moment to expand on why sound cards tend to last so long. To be frank, the market for them has largely stagnated.

Games used to drive the demand for hardware-accelerated audio, but that feature has all but disappeared from recent titles. Creative’s EAX positional audio scheme died years ago. OpenAL was supposed to be a replacement of sorts, but Creative’s list of games with OpenAL audio hasn’t been updated since 2008. Blue Ripple Sound’s Rapture3D positional audio software is used by some Codemasters games, and it’s been made to work with a handful of OpenAL titles. However, Blue Ripple Sound is quite explicit about the fact that its algorithms run on the CPU.

The fact is today’s multi-core processors have an abundance of horsepower. Crunching numbers for positional audio shouldn’t be a challenge. These days, developers typically handle positional audio processing in software. Some, like Battlefield 3 maker DICE, even offer their own virtualization voodoo.

Perhaps because the need for hardware acceleration has waned, the flow of new audio processors has slowed to a trickle. We’ve had plenty of output channels and real-time encoding options for quite some time, leaving few reasons for fresh silicon.

The older audio processors that dominate the market are designed for the PCI interface, which is quickly falling out of favor among motherboard makers. Intel dropped PCI support from its consumer desktop platforms years ago, forcing board makers to employ third-party silicon if they want to offer PCI slots. Most still do, but it probably won’t be long before the majority of new boards are PCIe-only.

Since the C-Media audio processors used in the Xonar line lack native PCIe support, Asus has taken to using bridge chips to link up with the newer interface. The DGX and DSX both feature PLX’s PEX8112 bridge chip, just like the other PCIe members of the ever-growing Xonar family. Bridged solutions aren’t quite as slick as native ones, of course, but we’ve yet to see any issues related to Asus’ use of the PLX chips.

In the picture above, you can see the bridge chip next to C-Media’s Oxygen HD CMI8786 audio processor on the Xonar DGX. That’s the same C-Media chip as on the older DG model. Likewise, the DSX features the same Asus AV66 audio processor as the Xonar DS. Though Asus’ name is silkscreened on the surface, the AV66 is actually a C-Media CMI8788. Asus tells us the AV66, AV100, and AV200 processors featured on its Xonar cards are all variants of the CMI8788 with different software packages.

We’re at a loss as to why Asus doesn’t have its own name branded across the CMI8786. That chip is a custom order just for the Xonar DG and DGX. The CMI8786 is really just a cut-down version of the CMI8788. Both chips can handle 24-bit audio, but the CMI8788 does so at sampling rates up to 192kHz, while the CMI8786 tops out at 96kHz.

As the model numbers suggest, the CMI8788 can feed eight output channels, while the CMI8786 is capped at six. Translation: the Xonar DSX can power 7.1-speaker home theaters, while the DGX is limited to 5.1-speaker setups.

Asus uses a different mix of complementary digital-to-analog and analog-to-digital conversion silicon on each card. The DSX pairs a six-channel Wolfson DAC with a stereo codec from the same company. Cirrus Logic supplies the conversion hardware for the DGX, which uses a similar DAC-and-codec combo. Incidentally, all of the DAC and codec chips offer 24 bits of resolution at 192kHz sampling rates. The Xonar DGX’s 96kHz limitation comes from its audio processor alone.

Xonar DGX Xonar DSX Interface PCI Express x1 PCI Express x1 Audio chip C-Media CMI8786 Asus AV66 Digital-to-analog converter Cirrus Logic CS4361 Wolfson WM8766G Wolfson WM8776 Analog-to-digital converter Cirrus Logic CS4245 WolfsonWM8776 Headphone amp Texas Instruments DRV601 NA Replaceable op-amps? No Yes Maximum recording quality 24-bit/96kHz 24-bit/192kHz Maximum playback quality 24-bit/96kHz 24-bit/192kHz Output signal-to-noise ratio 105 dB 107 dB Input signal-to-noise ratio 103 dB 100 dB Output channels 6 8 Multi-channel digital encoding NA DTS Interactive Speaker virtualization Dolby Headphone DTS Neo:PC* Street price $40 $49

The published signal-to-noise ratios of each card give us a general sense of their overall signal quality. Looks like the Xonar DGX might be the more balanced of the two; it has a 105-decibel output SNR and a 103-dB input SNR. The DSX has higher output SNR, at 107 dB, but its 100 dB input SNR is a little low.

The Xonar DGX is the less expensive of the two cards, but by less than the cost of a super-sized McDonald’s combo. Deciding between the two may be more a factor of whether you intend to hook up the card to a fancy home-theater receiver or run it through a headset or headphones. We’ll explore the features tailored to each setup as we take a closer look at each card.

Say hello to the Xonar DGX

First up, the $40 Xonar DGX. Its predecessor, the Xonar DG, has been one of our most recommended sound cards for quite some time. Naturally, we’ve been anticipating its PCI Express successor.

We’re a little miffed by the attached premium, though. The original costs just $25 right now, so you’re paying an extra $15 for the PCIe upgrade. I suppose that’s not so bad if one considers the expenditure an investment in future compatibility.

Although the PLX bridge chip consumes some additional board real estate, the Xonar DGX is still built on a half-height expansion card. The circuit board is 2.5″ tall and 6.7″ long, and Asus includes a half-height backplate in the box.

Along the top edge of the card, you can see a number of internal connectors for extra input and output ports. In addition to auxiliary input and S/PDIF output headers, a front-panel headset connector is provided. So long as your case has the necessary ports up front, there’s no need to rummage around behind your PC to hook up headphones or a mic.

The front-panel headphone and primary front-channel output are both equipped with Texas Instruments DRV601 headphone amplifiers. In the picture above, one of the chips can be seen sitting between two clusters of capacitors near the card’s top edge. The onboard amps have three operating modes tuned for different headphone impedance ranges. Choose the one that matches your cans, and you’re set.

Like the Xonar DG that came before it, the DGX has been programmed to give certain elements, specifically vocals and percussion, a little more oomph. We liked this extra kick when we first heard it, but the artificial emphasis can sound a little harsh. Cyril’s ears seem especially sensitive to this special programming. He’s experienced fatigue when listening to the Xonar DG for long periods. Throughout our blind listening tests, he also said the DGX reminded him of the DG.

A typical assortment of ports lines the DGX’s backplate. On the far right, there’s a digital S/PDIF output for folks with compatible receivers or speakers. The Xonar DGX can’t encode digital bitstreams on the fly, limiting multi-channel digital output to pre-encoded tracks. Music and movies will work just fine, but gamers who want surround sound will have to use analog outputs. Three of those can be found next to a shared line/mic input.

The Xonar DGX might not be able to encode digital bitstreams in real-time, but it can virtualize multi-channel speaker setups using Dolby Headphone software incorporated in the drivers. With the Dolby scheme activated, users can choose from three room configurations that place the virtual speakers at different distances. Alas, The Dolby option appears only when headphones are the selected output. The DGX can’t fake surround sound with stereo speakers.

Asus’ Xonar driver control panel hasn’t changed for years, which is a bit of a shame considering how much work the firm has put into its recent motherboard software. The control panel covers all the basics in unspectacular fashion. It also has a few tricks up its sleeve.

The first of those is the little GX button in the lower-right corner. The label refers to GX 2.5, an Asus “gaming audio engine” that simulates the EAX positional audio effects of some older games. GX 2.5 works with the last version of EAX, which allowed for up to 128 simultaneous effects. That final version of EAX came out before Windows Vista, a really long time ago.

For its second driver trick, the Xonar DGX offers an echo-cancellation mode designed for folks with stereo speakers and desk-mounted microphones. It’s meant for voice communication applications, and Asus recommends disabling the feature unless you’re actively using Skype or the like. Aside from the mute and volume controls, the rest of the driver control panel is greyed-out when echo cancellation is enabled.

And now, the Xonar DSX

With a $49 asking price, the Xonar DSX costs just $7 more than the standard DS. That’s more like it. But the DSX still costs nine bucks more than the DGX, so it has to outdo its headphone-focused sibling.

If you haven’t been paying close attention, you’d be forgiven for mistaking the DSX for the DGX. The two look very similar, right down to the size of their half-height circuit boards. Like the DGX, the DSX comes with a midget backplate. The card also has the same internal input and output headers. However, there’s no headphone amp onboard.

Instead of boosting headphone output, the Xonar DSX lets users choose how to amplify stereo sound. The front channel is fed through a socketed operational amplifier that users can replace easily on their own. A chip-puller is ideal for the task, but the op-amp can be separated from the socket with no more than a small screwdriver.

The DSX’s op-amp socket is filled by a Texas Instruments NE55329. Asus told us at the Computex trade show earlier this year that socketed Xonars are outfitted with neutral-sounding op-amps by default. If users crave a particular acoustic profile, they can swap in a different chip.

Because it applies to just the front channel, the op-amp can only shape the sound coming out of two speakers. Headphones plugged into the green port at the rear will be affected, but the op-amp doesn’t touch signals going to the front-panel headphone connector or to the card’s rear, side, or center/sub outputs.

With one more output channel than the Xonar DGX, the DSX has to resort to sharing to fit all of its ports on a half-height card. The rear-channel output uses the same jack as the digital S/PDIF out. Asus includes a TOS-Link adapter for the 3.5-mm port, but you’ll need to supply your own optical cable to use the digital connection.

There’s some temptation to go digital, because the Xonar DSX supports DTS Interactive, a real-time encoder capable of mixing surround-sound bitstreams on the fly. Everything from games to movies can be pumped to a compatible receiver or speakers over a single digital cable instead of the mass of analog cords usually required. The Xonar’s DTS implementation also features Neo:PC, which can expand stereo sources to pseudo-surround sound. Neo:PC comes with strings, though. It has to be used with DTS Interactive, restricting surround-sound simulation to digital output.

The Xonar DX’s drivers look all but identical to those of the DGX. A few of the options are different, but the two drivers share a common interface. They have the same mixer and equalizer, plus access to the same suite of effects.

Of course, the DSX drivers have a few special knobs to twirl related to DTS. The DTS Interactive mode features a speaker shifter that allows users to map how their speakers are laid out in the room. The software should adjust the audio fed to each speaker accordingly. Folks can also tweak a couple of sliders related to how Neo:PC expands stereo sound. There’s no echo-cancellation mode, though.

Our testing methods

If you’re already familiar with our testing methods, feel free to skip ahead to the performance results on the next page. The information below is mostly nerdy details about system and test configurations. We present this information for reference, and we won’t be offended if you skip it.

As we said in the intro, the Xonar DGX and DSX will face off against our favorite mid-range sound card, the $88 Xonar DX. The DX has been featured in countless iterations of our System Guide, and it will be interesting to see how the cheaper cards fare against their older brother. (The Xonar DX is a PCI Express card, just like the DGX and DSX.) We’ve also included our motherboard’s “free” integrated audio, which is powered by a Realtek ALC898 codec.

Admittedly, the Sandy Bridge-E platform we used for testing is a little high-end for the budget Xonars. We wanted to make sure we were using a solid implementation of Realtek’s latest codec, though. Also, the testing associated with Cyril’s recent look at hardware-accelerated video transcoding monopolized a couple of the less expensive CPUs we have at TR’s northern outpost.

As ever, we did our best to deliver clean benchmark numbers. Tests were run at least five times, and we’ve reported the median result.

Our test system was configured like so:

Processor Core i7-3890X Motherboard Asus P9X79 PRO Chipset Intel X79 Express Memory size 16GB (4 DIMMs) Memory type Corsair Vengeance DDR3 SDRAM at 1600MHz Memory timings 9-9-9-24 1T Chipset drivers INF update 9.2.3.1022 Rapid Storage Technology Enterprise 3.1.0.1068 Graphics Asus Radeon HD 7970 DirectCU II TOP with Catalyst 12.6 drivers Audio Asus Xonar DGX with 7.12.8.1800 drivers Asus Xonar DSX with 7.12.8.1800 drivers Asus Xonar DX with 7.12.8.1794 drivers Integrated Realtek ALC898 with 2.70 drivers Hard drive Intel 520 Series 240GB SATA Power supply Corsair AX850 OS Windows 7 Ultimate x64 Edition Service Pack 1 DirectX 11 June 2010 Update

Thanks to Intel, Corsair, and Asus for helping to outfit our test rigs with some of the finest hardware available. Asus supplied the sound cards for testing, as well.

Unless otherwise specified, image quality settings for the graphics cards were left at the control panel defaults. Vertical refresh sync (vsync) was disabled for all tests.

We used the following test applications:

Some further notes on our methods:

We used the Fraps utility to record frame rates while playing a 90-second sequence from each game. Although capturing frame rates while playing isn’t precisely repeatable, we tried to make each run as similar as possible to all of the others. We tested each Fraps sequence five times per configuration in order to counteract any variability.

We measured total system power consumption at the wall socket using a Watts Up Pro digital power meter. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. The cards were plugged into a motherboard on an open test bench. The idle measurements were taken at the Windows desktop with the Aero theme enabled. The cards were tested under load running Battlefield 3 with the Ultra detail setting at 1920×1200.

For our blind listening tests, the output levels of each audio solution were equalized using RightMark Audio Analyzer and then tweaked by hand. With a couple different test signals, the levels RMAA told us were normalized sounded slightly off, so we had to resort to manual tuning. Each track in our listening tests was ripped from the original audio CD and saved as an uncompressed WAV file. Tracks were played using Windows Media Player 12 and a pair of Sennheiser HD 555 headphones. Our test subjects listened to 30-second clips of various songs back-to-back on different audio solutions. The listeners had no idea which solution was being played for them at any given time. To mix things up, the matchups were randomized for each song and test subject. There were six matchups per song, allowing each solution to be tested head-to-head with the others.

The tests and methods we employ are generally publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Gaming

The last time we looked at the impact of different audio solutions on gaming performance, the results were a wash. We weren’t expecting much of a difference this time around, so to make things interesting, we busted out the test methods we introduced in Scott’s article, Inside the second: A new look at game benchmarking. In addition to measuring frame rates, we’ve measured individual frame times, which provide a much better picture of overall smoothness.

Rather than burying you under a deluge of frame-time graphs, we’ll stick to a couple of results for each game: average frames per second and 99th percentile frame times. The FPS figures should be familiar to anyone who’s read a PC hardware review in the last decade. The 99th percentile numbers refer to the time below which 99% of all frames are rendered. Lower frame times translate to higher frame rates and smoother gameplay.

Finding PC games with audio options that extend beyond simple volume controls proved rather difficult, so our gaming tests are limited to Battlefield 3 and DiRT Showdown. Let’s start with BF3, which features an “Enhanced” audio mode that provides surround-sound virtualization for stereo output. Our testing was conducted with headphones, so we tested each card with standard stereo output and with BF3‘s Enhanced mode enabled. Since the Xonar DGX and DX both support virtualization via Dolby Headphone, we tested those configurations, as well.

To make the graphs easier to read, we’ve colored-coded the results. The Xonar DGX and DSX both appear in dark blue, while the results for the older DX are painted a lighter shade. We’ve grayed out the bars for the Realtek integrated audio.

Not much to see here, folks. Less than a single frame per second separates the various solutions in Battlefield 3. Our 99th percentile frame time results are just as conclusive, with only a 0.6-millisecond gap between the fastest and slowest configurations.

Next, we’ll tackle the latest chapter in the DiRT franchise. This game offers standard software audio in addition to a Rapture3D mode with its own virtualization magic. We tested both modes on each config, and we ran another set of Dolby Headphone tests on the cards that support it.

With a very different game, we see largely the same results. The various configurations are tightly packed within a span of 2.7 FPS and 1.3 milliseconds, depending on the metric.

Gaming performance has long been gated by one’s graphics card and, to a lesser extent, the CPU. It’s been a long time since sound cards had any major impact on the equation.

Input latency

We measure input latency with Audacity, the free audio editor used by our own podcast producer to piece together the various audio streams we generate during recording sessions. The latency test follows these instructions in the official Audacity manual.

All of the Xonars have longer input latencies than the Realtek codec. The DGX is a little slower than the DSX, but the difference there is just 18 milliseconds. The gap between the quickest Xonars and the Realtek implementation is much larger, at 50 milliseconds. Hearing a difference between the delays might be difficult for end users, though.

Power consumption

System power draw was measured first at idle and then in Battlefield 3 using the same configurations as in our gaming performance tests.

As one might expect, adding a sound card will increase system power consumption. However, the difference doesn’t amount to much. The Realtek config saves only a few watts at idle and less than 10W under load. Among the Xonars, the DSX is the most power-efficient, particularly when playing Battlefield 3.

Blind listening tests

We believe the best way to evaluate sound cards is to listen to them in blind tests. Subjective impressions provide a sense of how each solution sounds, and blind tests largely remove bias from the equation. Our victims subjects listened to 30-second clips of various songs back-to-back on different audio solutions, and they had no idea what solution was being played when.

Since they’re the limiting factor, let’s introduce our listeners. They’ve all rated themselves on an impromptu audiophile scale between 0, which considers Apple’s stock iPhone earbuds to be awesome, and 10, which classifies as garbage anything that isn’t piped through multi-thousand-dollar speakers via gold-plated Monster cables from an original vinyl recording.

Brent, a friend of mine from university, was first to endure our barrage of 30-second song clips. He doesn’t have any fancy audio gear and rates himself a 6 on our scale. Next, I convinced my girlfriend Mo to sit through a session. She thinks even basic Logitech speakers sound great, so we’ll give her a 4 on the audiophile scale. TR staffer Cyril is definitely pickier when it comes to sound quality; he rates himself an 8. After one round of listening tests, Cyril took the controls and ran a second round with me in the hot seat. I’m not sure my ears are quite as sensitive as Cyril’s, but I do appreciate good sound, and I’d give myself the same audiophile rating.

Die Antwoord — Hey Sexy

There isn’t a whole lot of hip-hop in my music library, but I do have a weakness for South African rap group Die Antwoord. Hey Sexy layers vocals over looping guitars and a thumping bass line.

To my ears, Hey Sexy was “more gangsta” on the DSX than on the DGX. The former’s bass line was almost over-emphasized, and the card was difficult to distinguish from the more expensive Xonar DX. The DGX sounded less boomy in comparison, with more prominent mid-range content and in-your-face vocals.

Cyril found the DGX more balanced than the other Xonars, perhaps because its bass was less prominent. He thought the DSX sounded a little metallic at the high end, as well. Cyril actually liked the sound of the Realtek codec versus the DGX and DSX.

Our other listeners agreed with the general sentiment that the Xonar DSX and DX offered the most bass of the bunch. Mo had a hard time telling the difference between those two, but Brent thought the DSX thumped a little harder. He also heard more pronounced vocals on the Xonar DGX, something that Mo didn’t notice. Neither was particularly keen on the Realtek codec, which was singled out for lacking richness, being too tinny and rattly, and having too much treble.

LCD Soundsystem — Home

In the realm of increasingly difficult-to-classify modern music, LCD Soundsystem is perhaps best described as low-fi indie electronica. Home is from the band’s final album. The track is an upbeat number filled with different instruments, some of which sound more familiar than others.

The Realtek codec failed to impress my ears with this song, and Cyril thought it sounded a little neutered. For me, the Xonar DSX offered better separation between the various instruments than the integrated motherboard audio. It also sounded more balanced than the DGX, which emphasized the mid- and high-range notes. That emphasis wasn’t as apparent versus the Xonar DX.

Cyril and I both found the Xonar DSX and DX to be comparable. He seemed to prefer the Xonar DGX over the DX due to the DGX’s greater separation between the song’s percussive elements. When the DGX was played back-to-back with the DSX, though, that separation sounded a little over-sharpened to his ears.

With this track, our other listeners struggled to tell the different configs apart. Mo preferred the DSX to the DGX in their head-to-head matchup, but she couldn’t explain why. Brent favored the DGX, which he said had more distinct vocals and treble.

Adele — Rolling in the Deep

It’s rare to hear music I like playing in malls and department stores, but Adele’s 21 is one of those albums. The first track, Rolling in the Deep, combines Adele’s soulful voice with background vocals, bass, and a building piano track.

Once again, the Xonar DSX was a close match for the DX. All of the listeners agreed on that point, although there were differing opinions about the subtle differences between the two. To me, the DSX felt farther from the stage. Brent said it had deeper lows, but Cyril thought the opposite, adding that the DSX’s vocals sounded a little metallic and less fleshed out than on the Xonar DX.

There was less consensus regarding the DGX, which some said offered clearer backing vocals and percussion. However, Cyril thought the DGX’s vocals sounded like a “robot singing through a tin can.” He also found the card’s mid-range frequencies to be a little compressed, at least versus the other Xonars. Cyril didn’t think the Realtek codec sounded as good as the DGX, but it sounded better to me due to a more even distribution of frequencies. To my ears, the DGX’s vocals were over-emphasized, with a hint of distortion. Mo heard some distortion in the DGX’s percussion, too.

Mo was reasonably happy with the Realtek codec overall, although she said it sounded a little tinny. Brent was less impressed, saying the Xonars were “just better” in all their matchups. With few exceptions, Cyril and I agreed. To my ears, the onboard audio didn’t have as much body as the Xonar DSX. Cyril repeatedly called the Realtek solution neutral, but he did feel that its lows were a little muted compared to the discrete cards.

The Tea Party — Sister Awake

Apparently, few people outside of Canada and Australia have heard of The Tea Party, which sounds a little like Jim Morrison singing for Led Zeppelin somewhere in eastern Asia. The snippet of Sister Awake we used is purely instrumental and filled with multiple string and percussion instruments.

In our marquee matchup, the Xonar DSX versus the DGX, the results were mixed. Mo couldn’t tell the difference between the two, but the rest of us could. Cyril thought the DGX was a little bit louder, and that the DSX’s drums blended in with the mid-range a little. Brent said the DGX offered too much treble at the high end of the spectrum, to the point that it sounded tinny. I agreed with those sentiments and thought the percussion hit harder on the DSX.

To my ears, the Realtek codec sounded squished together compared to the DSX. I did think the onboard audio was pretty close to the DGX, though. Cyril thought the Realtek solution’s drums were a bit subdued, with more of a focus on the mid-to-upper range of the spectrum.

Personal preferences inevitably taint subjective impressions, especially when subjects are simply asked what they hear. That’s probably why Brent preferred the motherboard audio’s more prominent mid-range tones to the stronger bass on the Xonar DX and DSX. Mo was firmly in the Xonar camp across the board and liked the DSX more than the others.

Tom Waits — Tell Me

Tom Waits’ unmistakable voice sounds like what might happen if one gargled gravel every day for 20 years. In Tell Me, Waits’ rough vocals are complemented by subtle percussion, sparing guitars, and what I believe is a xylophone. With Waits, one never knows.

Half of our listeners couldn’t distinguish between the Xonar DGX and DSX this time around. Cyril and I had little trouble, however. He found the DGX’s mids too sharp and the DSX more natural, while I thought the DSX had more low-end grunt and sounded a little subtler than the DGX.

I preferred the DSX to everything else it went up against. Cyril liked the DSX over the Realtek solution, which he said had no warmth, but he said the vocals were crisper on the DX.

Neither of us really liked the motherboard’s built-in sound, calling it compressed and “slightly wrong.” Brent was similarly critical of the Realtek audio, saying its rivals sounded fuller in comparison. He called the Xonar DX and DSX similar, and said Waits’ deep voice was accentuated by the DGX. Cyril made a similar comment, noting that Waits’ voice sounded more natural on the DGX. That may be the only time such a raspy bellow has ever been described as natural.

Mo didn’t mind the Realtek audio as much as the rest of us, perhaps because listener fatigue had set in. She thought the Xonar DGX was a little crisper than the other Xonars, though.

The inevitable summary

Our listeners all thought the different audio solutions were more closely matched than in any of the listening tests we’ve conducted before. Their assessments of each config were largely consistent, but some of the songs and matchups teased out contradictory opinions. More often than not, the Xonar DSX was identified as having deeper bass and a fuller sound than the DGX. The DGX’s mid-range bias was definitely apparent, and its output was often deemed sharper and crisper than the DSX and its other rivals.

Although it fared better than any other integrated audio implementation we’ve tested, the Realtek codec was clearly inferior to the DGX and DSX overall. The onboard audio was definitely short on bass, and it lacked the sharper mid-range tones of the DGX.

We weren’t surprised to see the motherboard audio fall to the bottom, but we didn’t expect the Xonar DSX to so closely match the pricier DX. Those two sounded more alike than any other pair, and our listeners usually preferred the DSX.

A few words about gaming audio quality

During our music listening tests, subjects had the luxury of closing their eyes and concentrating on sound alone. Getting a sense of gaming audio quality is more difficult because the soundtrack tends to fade into the background when you’re actually playing. We didn’t run a full set of blind listening tests in games, but I did take a few notes while testing Battlefield 3 and DiRT Showdown.

The biggest takeaway was that I didn’t hear obvious differences in audio quality between the various solutions. Perhaps I was too distracted by the visuals and trying to play through the games in a repeatable fashion, so that I’d hear the same mix of sounds. Maybe the differences faded when it took minutes rather than seconds to swap sound cards.

There were, however, very big differences between the audio configurations offered by each game. Battlefield 3‘s Enhanced-mode surround virtualization added a real sense of immersion in the environment, especially with gunfire coming from all directions. The Dolby Headphone mode on the Xonar DGX and DX had similar surround content, but it sounded a little more distant and muffled. Remember that Dolby Headphone attempts to simulate sound coming from speakers at a distance. Personally, I prefer the in-game Enhanced mode.

In DiRT Showdown, there was a pronounced difference between the built-in software and Rapture3D audio modes. The latter felt natural, with in-game sounds at more appropriate distances than the default audio, which kind of crammed everything right into my ear. Again, Dolby Headphone output sounded a little muffled and far away—and not as good as the Rapture3D surround mode.

RightMark Audio Analyzer playback quality – 16-bit/44.1kHz

This is where we get really geeky. If you’re not interested in things like frequency response, dynamic range, or intermodulation distortion, you’ll be forgiven for jumping straight to the conclusion. Seriously, congratulations for making it this far.

We’re moving onto some objective evaluations of analog signal quality using RightMark Audio Analyzer. Our first test probes the front-channel output of each card using a test signal recorded by a high-end Xonar Xense on a separate system. We ran this test with 16 bits of resolution at 44.1kHz, a perfect match for CD audio.

To keep things simple, we’ve translated RightMark’s word-based quality scale to numbers. Higher scores reflect better audio quality, and the scale tops out at 6, which corresponds to an “Excellent” rating.

RightMark Audio Analyzer playback quality – 16-bit/44.1kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC898 6 4 4 5 3 4 5 5 5 Xonar DX 6 4 4 6 3 4 5 5 5 Xonar DGX 5 4 4 6 3 4 5 5 4 Xonar DSX 5 4 4 5 3 4 5 5 4

Surprisingly, the Xonar DGX and DSX score lower than the Realtek integrated audio. The numbers are pretty close across the board, though. No more than one point separates any of the cards from the others.

We have some more detailed RMAA graphs below. They’re a little indulgent, we’ll admit, but that’s sort of our style. We’ve put frequency response first because it’s one of the most important elements. Notice how the Xonar DGX falls off at higher frequencies, while the others hold the line for longer. Apart from the Xonar DX having a little more intermodulation distortion, the rest of the results are pretty close.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

RightMark Audio Analyzer loopback quality – 16-bit/44.1kHz

Next, we have a series of “loopback” tests that run the front-channel output through the line input, giving us a sense of overall signal quality. We’ll use CD-quality audio again for this round.

RightMark Audio Analyzer loopback quality – 16-bit/44.1kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC898 6 4 5 5 3 5 6 5 5 Xonar DX 6 6 6 6 4 6 6 6 6 Xonar DGX 6 5 5 6 4 6 6 6 5 Xonar DSX 6 5 5 6 5 6 6 6 5

In our first loopback tests, the Xonar DX takes the top honors. The Xonar DGX and DSX look evenly matched and better than the Realtek audio overall.

Before you flick that scroll wheel, check out the Xonar DGX in the frequency response plot. Again, it starts dropping at lower frequencies than the competition. Also worth noting: the higher noise and distortion exhibited by the integrated audio in several of the graphs.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

RightMark Audio Analyzer loopback quality – 24-bit/96kHz

Our loopback tests continue with a higher sampling rate and resolution.

RightMark Audio Analyzer loopback quality – 24-bit/96kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC898 5 5 5 5 3 4 6 4 5 Xonar DX 6 6 6 6 6 6 6 6 6 Xonar DGX 5 6 6 6 4 6 6 6 5 Xonar DSX 5 6 6 6 4 6 6 6 5

The standings don’t change according to our numerical scale. The Xonar DX scores sixes across the board, while the DGX and DSX both outscore the Realtek audio. I’m not sure I trust the math RMAA is using to generate the “overall” ratings. The ALC898 seems to be ranked too highly considering the lower scores it has in several of the individual tests.

Scroll slowly, because the plots are more interesting this time around. The Realtek audio falls off a cliff much earlier than the Xonars in the frequency response graph. It has higher noise and distortion levels, too, with huge spikes at higher frequencies. Noise and distortion are the biggest differences between the Xonar DGX and DSX and their more expensive sibling, although without the erratic behavior of the ALC898.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

RightMark Audio Analyzer loopback quality – 24-bit/192kHz

Our second-to-last RMAA test cranks the sampling rate up to 192kHz. The Xonar DGX tops out at 96kHz, so it has to sit on the sidelines.

RightMark Audio Analyzer loopback quality – 24-bit/192kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC898 5 5 5 5 3 5 6 5 5 Xonar DX 6 6 6 6 6 6 6 6 5 Xonar DSX 5 6 6 6 4 6 6 6 5

Ignore the overall score and focus on the rest of the numbers. The Xonar DX has a slight advantage over the DSX in a few tests, and both outscore the Realtek audio in the majority.

The graphs below bear out those results. The ALC898 repeats its early exit in the frequency response plot, and its high noise and distortion levels persist. Overall, the Xonar DSX has more distortion and noise than the DX, but neither jumps around like the Realtek codec.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

Signal quality under load

Not content to go overboard with four sets of RMAA results, we added a fifth. For this final round, we tested each solution’s loopback signal quality under a heavy system load consisting of AIDA64’s CPU stress test, the Unigine Heaven graphics benchmark, and a file transfer from a SATA SSD to another solid-state drive attached to one of the motherboard’s USB 3.0 ports. We’ve seen much lesser loads taint the output quality of older integrated audio solutions, and we were curious about what would happen to our contenders with the system pushed to its limits.

We ran our load test on each solution at its highest quality setting. The Xonar DGX used 24-bit/96kHz audio, while the others were set to 192kHz at the same resolution.

RightMark Audio Analyzer loopback quality – Load Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC898 5 6 6 5 4 5 6 5 5 Xonar DX 6 6 6 6 5 6 6 6 5 Xonar DGX 5 6 6 6 4 6 6 6 5 Xonar DSX 5 6 6 6 4 6 6 6 5

I had high hopes for this test, but it didn’t end up illustrating much. For the most part, the individual scores were no different than the results of tests we conducted with nothing else going on in the background. In some cases, the load results generated slightly higher scores. We may have to try this test with some cheaper motherboards. Clearly, the audio implementation on our high-end Asus motherboard is well-insulated from system loads.

RMAA won’t plot results with different sampling rates together, so we’re going to skip the extra graphs.