When building a new PC, today’s enthusiast faces numerous important questions. How many CPU cores do I need? Will a GeForce or a Radeon deliver the smoothest frame rates in the games I play the most? Can I afford a solid-state disk large enough to be useful as a system and applications drive? How quiet can I make the rig without sacrificing performance? Oh, and do I really need a sound card?

I bet you can tell where this is going.

Not too long ago, the answer to that last question would have been a unequivocal yes. There was a time when the “free” audio integrated on motherboards was almost universally horrendous. Early onboard sound implementations were plagued by poor-quality codecs and board-level interference that translated to lousy audio quality. They also lacked hardware acceleration for positional 3D audio, which was a big deal at the time.

Fast-forward to today, and the PC audio landscape has changed dramatically. Creative’s EAX positional audio standard is all but dead, and the rise of console ports seems to have squelched the need hardware-accelerated 3D audio entirely. Onboard solutions have gotten better, too, causing many to claim that modern implementations are more than adequate for most users. Some defend this position with the sort of passionate ferocity normally reserved for GPU flame wars. I’m not so sure, though.

You see, as integrated audio has improved, so have discrete sound cards. The iconic Sound Blaster may be stagnating, but other players are picking up the slack, notably Asus, whose family of Xonar sound cards has been growing faster than the Duggars. Asus first waded into the sound card market with the Xonar D2X, an ambitious high-end model that garnered a TR Editor’s Choice award on its maiden voyage. Now, some three years later, Asus is celebrating the Xonar’s anniversary with a new model dubbed the Xense. Bundled with a gaming headset from Sennheiser, the Xense has all the trappings of a fancy sound card: high-quality DACs, replaceable OPAMPs, 1/4″ jacks, a headphone amp, and support for multichannel analog and digital output. At $280 online, it’s definitely a luxury item, perhaps too big a step up for someone unsure whether they even need a sound card.

Fortunately, the Xense isn’t the only fresh addition to the Xonar lineup. Asus has also rolled out the Xonar DG with a much more affordable $30 street price. The DG isn’t nearly as indulgent as the Xense, but its low cost gives us the perfect opportunity to explore what even a modest audio upgrade can do for a PC otherwise relying on an integrated Realtek codec. So we have, and we’ve thrown the Xense into the mix to see whether it’s worth the additional expense. Keeping reading to find out.

Much more than an audio codec

When integrated on a motherboard, audio is usually handled by a single codec chip. Apart from the processing done in software by an associated driver, this lone piece of silicon is responsible for translating binary bitstreams into something that can be output to your speakers or headset. That’s quite an important role, but as is too often the case, motherboard makers tend to opt for the simplest and cheapest implementation that will get the job done. I understand their dilemma, at least to some extent. Audio must compete with other peripheral chips in a world where board real estate is at a premium, and it’s not really as sexy as USB 3.0 or 6Gbps SATA.

Obviously, discrete solutions have a natural advantage. Not only do they get to focus solely on delivering quality sound, they can also spread out on an expansion card. With plenty of room to breathe, sound cards are free to tackle tasks that would otherwise be performed by a single audio codec with a small army of chips and auxiliary components.

An audio processor is at the center of this web of additional hardware, and the market is currently dominated by two camps: Creative’s X-Fi derivatives and the various flavors of C-Media’s Oxygen HD. The latter is favored by Asus, which sometimes hides an Oxygen under silk-screening bearing its own name. Such is the case with the Xense, whose “Asus AV100” audio processor is, in fact, a C-Media CMI8788. We first encountered this Oxygen HD chip in early 2007, and it’s been around the block a few times since. The fact that the CMI8788 is still relevant is a testament to just how little the PC audio market has moved in the last few years.

Audio standards haven’t really budged since the chip’s introduction, for example. The Oxygen HD is capable of handling 24-bit resolutions at sampling rates up to 192kHz, which is as high-definition as consumer audio gets. With eight output channels, the C-Media chip is also equipped to feed elaborate 7.1-speaker home-theater setups. To this formula, Asus adds surround-sound speaker virtualization via Dolby Headphone and the ability to encode multichannel digital bitstreams on the fly with Dolby Digital Live.

For folks who play older games that make use of EAX effects, Asus has also implemented GX2.5, the latest version of its EAX emulation scheme. GX2.5 can juggle up to 128 simultaneous positional audio effects, which is as many as are available with Creative’s latest version of EAX. To give you a sense of how old that standard is, the last revision, EAX 5.0, debuted with the original X-Fi more than a half-decade ago.

Asus declined to add its own name to the audio processor that graces the Xonar DG, although the company informs us that this CMI8786 is a custom order. The chip has Oxygen HD heritage and can be best thought of as a cut-down version of the CMI8788. 24-bit audio is still supported, but only at sampling rates up to 96kHz. The number of output channels has been reduced to six, and there’s no provision for real-time multichannel encoding for digital output. However, Dolby Headphone is still included, and so is GX2.5. Folks using analog speakers or headphones aren’t likely to need much more.

Of course, the audio processor is only responsible for sound when it’s expressed in ones and zeroes. The DACs tasked with translating digital audio into an analog signal can make or break a card’s output quality, at least with the sort of speakers and headphones most plug into their systems. On the Xense, a “Burr Brown” stereo DAC from Texas Instruments handles the front-channel out, while a Cirrus Logic chip takes care of the rest of the outgoing channels. Cirrus logic is also responsible for the Xense’s ADC, which takes care of digital conversions for the card’s analog input.

Xonar DG Xonar Xense Interface 32-bit PCI PCI Express x1 Audio chip C-Media CMI8786 Asus AV100 Digital-to-analog converter Cirrus Logic CS4361 Texas Instruments PCM1796 Cirrus Logic CS4362A Analog-to-digital converter Cirrus Logic CS4245 Cirrus Logic CS5381 Headphone amp Texas Instruments DRV601RTJR Texas Instruments 6120A2 Replaceable OPAMPs? 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 118 dB Input signal-to-noise ratio 103 dB 118 dB Output channels 6 8 Multi-channel digital encoding NA Dolby Digital Live! Speaker virtualization Dolby Headphone Dolby Headphone Street price $30 $280

Things are a little simpler on the Xonar DG, whose analog outs are fed solely by a Cirrus Logic DACone with a 104-dB signal-to-noise ratio that’s is notably lower than that of the Texas Instruments and Cirrus chips on the Xense, which are rated at 123 and 114 dB, respectively. I suspect the DG’s Cirrus Logic ADC isn’t quite as good as the one sitting on the Xense, either, although we’ll be able to get a sense of things with some “loopback” audio tests a little later in the review. For what it’s worth, Asus pegs the Xense’s overall output and input SNR at 118 dB, while the DG’s outputs are listed at 105 dB and its input at 103 dB.

Built-in headphone amplification is something you won’t find on a motherboard, but it’s featured in both Xonars. On the DG, Asus has gone with Texas Instruments’ DRV601RTJR, which is optimized for headphone impedances of 32-150 Ω according to the card’s spec sheet. The Xense gets something considerably fancier: a TI amp capable of pushing headphones with impedances up to 600 Ω. Of course, the headphones bundled with the card are rated for an impedance of only 150 Ω. Mid-range stereo cans like Sennheiser’s excellent HD 555s, which we use for listening tests, have a rated impedance of just 50 Ω. You don’t need big numbers for high-quality sound.

Say hello to the Xense

Asus hides much of the Xense’s hardware under an EMI shield polished to a mirror-like finish. This thin metal piece is contoured to match the cup shape of the included headset, which is a nice aesthetic touch. So is the faux-chrome, although you’re not going to see much of it with the card buried inside a case.

The shield is held in place by five screws secured by a smidgen of blue Loctite. You’ll need to remove these screws and lift the shield to gain access to the Xense’s replaceable operational amplifiers, or OPAMPs. The stock JRC units tied to the front-channel output can be swapped for units of your choice. Asus even sells its own OPAMP upgrade kit for the card: a $10 package that includes a pair of LME49720 chips from National Semiconductor. Newegg is actually throwing the upgrade kit in for free if you buy a Xense before the end of the year.

The card itself is a full-height affair measuring 6.6 inches (168 mm) long. It’s actually the same length as the Xonar DG, although unlike the budget model, the Xense has a PCI Express x1 interface. Since the AV100 Oxygen HD audio chip was built to ride a PCI bus, Asus has to use a PLX bridge chip to tap into modern PCIe slots. Bridging isn’t as slick as a native PCIe implementation, but those are scarce in the audio world. Sound cards aren’t exactly hurting for bandwidth, anyway, and we’ve had no problems with other bridged Xonars.

A standard PCI Express x1 slot is only equipped to supply up to 10W of power. That’s not ideal for the Xonar Xense, which has a four-pin Molex connector for auxiliary juice. We’ll test power consumption a little later in the review to see whether the Xense is particularly thirsty.

Over to the right of the power plug and just out of the frame in the picture above, the Xense offers headers for a front-panel connector, an auxiliary digital input, and an S/PDIF output. These internal ports are complemented by an array of additional jacks that poke out of the rear expansion plate.

Alongside quarter-inch headphone and microphone ports, the Xense has a digital S/PDIF output with an RCA plug. In between those ports sits what looks like a gold-plated DVI connector. That isn’t a video output, though.

Instead, the port feeds an eight-channel array of 1/8″ analog audio jacks. That means no more crawling around under your desk to switch between headphones and a surround-sound speaker setup, and no jack sharing for the microphone input. Asus also throws in 1/4″ adapter for 1/8″ devices and a TOS-Link converter for the S/PDIF output.

You’ll also find an entire headset in the boxand not just a token throw-in, but a special version of Sennheiser’s PC 350 gaming headset, which normally sells for $180 on its own. These closed cans have 38-mm dynamic speakers backed by neodymium magnets. Sennheiser claims a frequency response of 10-26,000Hz and distortion of less than 0.1%. The adjustable boom mic has noise canceling built in and a 50-16,000Hz rated frequency response.

While testing the Xonars, I found the PC 350 to be comfortable to wear for hours at a time, and I quite like how the headset folds flat for transport. I expected the closed design to make my ears sweat, but much to my surprise, these Sennheisers feel a little cooler than our HD 555 headphones, which are an open design, albeit one with fuzzy earmuffs that seem to retain heat. The PC 350’s closed cups definitely do a better job of insulating the user from his surrounding environment, which you may prefer depending on whether you use headphones to avoid disturbing others or vice versa.

Sennheiser’s standard PC 350s have 1/8″ headphone and microphone jacks connected to nearly 10 feet of cabling. The Xense edition keeps the cable length but swaps in quarter-inch jacks to match the card’s oversized ports. You also get an in-line volume dial and mute switch, both of which should be useful for gamers and Skype users alike.

Although we’re going to concentrate on the sound cards today, I should take a moment to give my impressions on the PC 350s. I don’t have a lot of experience with gaming headsets outside of Psyko’s funky 5.1-channel model, but I do use a pair of HD 555 headphones with regularity, and I have a bit of a picky ear. When compared to the HD 555s, which can be found online for under $100, the PC 350s sound to me like they’re a little short on body and richness. I can’t put my finger on anything more specific that’s lacking, and to be honest, the difference is quite subtle. Matching volume levels exactly is nearly impossible due to the Xense’s headphone gain needing to be adjusted to account for differing impedances, making a proper back-to-back comparison rather difficult to conduct.

I suspect some of my siding with the HD 555s may be a preference for how open cups sound versus the headset’s closed-cup design. One should also keep in mind that the PC 350 folds flat and incorporates a microphone, while the HD 555s are strictly headphones and more cumbersome to transport.

Lowering the DG’s profile

You won’t find much in the way of extras included with the Xonar DG. In fact, apart from the driver CD and manual, the only other item in the box is a shorter back plate for use with low-profile enclosures. The DG’s circuit board is just 2.5″ tall, allowing the card to squeeze into the sort of slim cases one might want to wrap around a low-power home-theater PC.

With fewer chips and associated electrical components, the DG doesn’t need as much board area as the larger Xense. One of the chips that’s missing is a PCI Express bridge, which isn’t necessary because the DG has an old-school PCI interface. I’d prefer PCIe connectivity, but that would surely add to the cost of the card, and it’s not like there’s a shortage of empty PCI slots out there. Even the latest and greatest motherboards tend to feature at least one PCI slot, and so do the microATX models you might be mulling for that low-profile build.

Given the DG’s smaller footprint and component payload, we’re not surprised to see that the card lacks an auxiliary power connector. The card does, however, have plenty of room for the same set of internal headers available on the Xense. The front-panel connector on both cards is HD-compliant, by the way.

Of course, the DG does give up some ground when it comes to external ports. 1/8″ audio jacks are provided for the six-channel outputs and the card’s microphone input. There’s also a TOS-Link digital S/PDIF output, but that’s it. Adding more ports would’ve compromised the card’s low-profile design, and this is a pretty good mix for a budget offering.

Incidentally, Asus covers its Xonar line with a three-year limited warranty for both parts and labor. Three-year warranties are pretty standard for PC components, and you won’t have to jump through any limited-time registration hoops to get full coverage.

Little difference in drivers

Perhaps in response to the massive excess of extraneous applications and other bloat that Creative bundles with its sound cards, the drivers that accompany Asus’ Xonars are pretty compact. A single control panel gives the user access to just about everything.

The latest drivers available for the Xonar DG, version 7.12.8.1792, are a little newer than the 1788 release users can download for the Xense. That may explain some slight differences in options between the two drivers, which are otherwise quite similar in terms of the functionality offered.

Users have access to more DSP modes with the Xense, although I tend to keep such things disabled. Do we really need separate modes for first-person shooters and driving games? Probably not.

If you’re playing older games, you should hit the GX button, which enables Asus’ EAX emulation mode. Over to the left, the main interface allows the user to configure Dolby Headphone and Digital Live output. When headphones are selected, it’s also possible to switch the headphone amp between a number of preset impedance ranges. True to form, the Xense’s drivers have an additional headphone setting that’s specifically optimized for the PC 350s. The DG’s drivers have no such setting, but you can still select from a few impedance ranges.

Asus adds one more bit of goodness to the Xense’s drivers: the ability to adjust the ASIO latency between 1 and 80 milliseconds. ASIO is a protocol designed to offer applications unfettered access to audio hardware, and it’s most commonly used by musicians and those involved with audio production. Desktop users won’t need to fiddle with ASIO settings, so the DG’s lack of such an option doesn’t really put it at a disadvantage for most folks. However, we will probe each card’s general input latency in a moment.

Our testing methods

Before diving into our test results, I should take the time to introduce the Realtek ALC892 codec chip that will be representing integrated motherboard audio. An apparent successor to the wildly popular ALC889, the ALC892 has yet to appear on Realtek’s website. However, it’s already started popping up on motherboards, including the Asus Sabertooth X58 model that will serve as the basis for our test system.

The Sabertooth is a high-end board, and it fared pretty well in the basic tests we use to probe analog audio signal quality in motherboard reviews. Today, it faces a much more demanding suite of tests against a pair of Xonars. I considered adding a few more sound cards to the mix but held back for a couple of reasons. First, there aren’t a lot of sound cards on the market, and most of the ones available are other Xonar models that have much in common with these two. Second, and perhaps more importantly, we typically see the biggest differences in our listening tests, which become increasingly difficult (and time-consuming) to conduct the more sound cards are added to the mix.

Our gaming and latency tests were run five times, and we reported the median of the scores produced. We used the following system configuration for testing:

We used the following versions of our test applications:

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

Most of the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Gaming

To see whether the Xonars offer improved gaming performance, I fired up a collection of recent releases. These titles don’t take advantage of the cards’ support for EAX emulation, but few will outside of the years-old fodder found in the bargain bin at your local Walmart.

The games were run at a 1920×1080 resolution with all their eye candy turned up. I ran through the same 60-second portion of each game at least five times while Fraps logged frame rates in the background. Those frame rates stayed silky smooth throughout, despite my pushing the antialiasing to 4X and turning anisotropic filtering way up. Graphics horsepower is easily the biggest bottleneck for gaming performance, and our test rig’s Radeon HD 5870 is well equipped to handle the load.

To give the Xonars a little bit of an extra challenge, I had them fake a surround-sound speaker environment using Dolby Headphone. The Realtek codec doesn’t have an equivalent option, but it can virtualize stereo speakers for headphone output, which is the setting I used to test our integrated motherboard audio.

Think a discrete sound card is going to improve in-game frame rates? Think again. We could have come up with a contrived scenario using an older game engine to illustrate the potential benefit of hardware-accelerated positional 3D audio, but the fact remains that modern games seem content to perform audio processing on the CPU.

At best, our tests show only a few FPS separating the various solutions. Given the inherent variability associated with manual Fraps runs through a given portion of each game, I’m inclined to call things equal on the gaming front.

Well, almost equal. The ALC892’s lack of surround-sound speaker virtualization is a definite weakness. Dolby Headphone isn’t a perfect substitute for a proper 5.1-channel speaker setup, but for gaming, I much prefer it to vanilla stereo output. The two-channel speaker setup faked by the Realtek codec is an improvement over standard headphone output, too. However, it’s definitely lacking next to the Dolby implementation, which feels more immersive.

Input latency

At the suggestion of TR regular morphine, we’ve added a simple latency test to our audio suite. This test follows the instructions laid out by the folks responsible for the Audacity audio editor, which is a free and open-source application used by our own Jordan Drake to weave the various audio streams we generate into a coherent podcast. What we’re measuring here is the latency between the front-channel output and the microphone input.

Interesting. The Xonars have slightly higher input latencies compared to the Realtek codec. Of course, we’re only talking about a difference of around 45 milliseconds, which is probably too short of a gap for most ears to detect.

Power consumption

Before moving onto our subjective listening tests, let’s take a moment to check on system power consumption. Power draw was measured, sans monitor and speakers, at the wall outlet using a Watts Up Pro power meter. We noted the power draw with the system at idle and while immersed in Call of Duty: Modern Warfare 2 using the same speaker virtualization schemes as our gaming tests.

Although the Xense consumes several watts more than DG at idle, the two are very close under load. The DG’s power consumption looks particularly modest considering that the system is only pulling one more watt than when it’s running off the integrated Realtek codec. That codec was disabled via the BIOS for all our discrete audio tests.

Blind listening tests

In my view, the best way to evaluate a sound card is to listen to, well, how it sounds. Plenty of folks insist they can hear a difference between integrated and discrete solutions, so we lined up the Xonars against our motherboard’s Realtek codec for a series of listening tests. These were blind tests, so our subjects had no knowledge of which audio config they were hearing at any given time.

After several years of sound-card testing, I’ve found that doing back-to-back listening tests with relatively short 30-second song clips is the best way to get listeners to pick out specific differences in playback quality. The listeners wore our Sennheiser HD 555 headphones for these tests, and each card’s output level was normalized to within 0.1 decibels using RightMark Audio Analyzer to measure the volume of a test tone. The ALC892, DG, and Xense all faced each other in a series of head-to-head matchups with each song clip, and the order of those matchups was randomized for each track and test subject.

Our music snippets were all ripped directly from the original audio CDs and saved as uncompressed WAV files. We played these tracks back using Windows Media Player 11, the default media player for Windows 7. Below, you’ll find our listeners’ impressions of how each card sounded versus the competition. However, before we get into the results, it’s worth taking a moment to introduce our listeners. I asked each to rate themselves on an impromptu audiophile scale between 0, which considers Apple’s stock iPod 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 source.

The first listener to run the gauntlet was Matt Trinca, a new writer of ours who lives conveniently close to the Benchmarking Sweatshop. Until recently, Matt relied on a mini-stereo system for audio playback. He only rates himself a 6 on our scale. Cyril also lives within range of my lab, and he was kind enough to not only sit through the listening tests but also run them so that I could become a blind subject. A bit of a connoisseur, Cyril uses Sennheiser HD595 headphones and puts himself at an 8 on our audiophile scale. I’d give myself an 8, as well, and I spend most of my time listening to music piped through a pair of Abit iDome speakers. Finally, I bribed my girlfriend, Mo, to sit through a round of tests with the promise of a backrub and an empty dishwasher. She had truly atrocious speakers before I migrated her to a pair of cheap Logitech units that she thinks sound phenomenal, so I’m going to give her a 4 on our audiophile scale.

Arctic Monkeys  Fluorescent Adolescent

A reasonably straightforward rock track, Fluorescent Adolescent combines just enough British attitude with the usual mix of radio-friendly guitars and drumming.

Matt had a hard time discerning the difference between configs with this track. He found the Realtek solution’s drumming to be more forceful than that of the Xonars, and thought the DG sounded a little muddier than the Xense. Mo said they all sounded roughly the same, but she preferred the DG for reasons she couldn’t put her finger on.

Cyril and I both detected a low hiss in the background with the Realtek codec, which I suppose made the rest of our testing somewhat less than perfectly blind, at least for us. He thought the integrated solution sounded a little artificial and preferred the DG for its crisper bass and superior separation, even versus the Xense. I singled out the Xense for better separation, but I still favored the sharpness of the DG’s percussion and vocals. To my ears, the background instrumentation sounded a little lost on the Realtek codec.

Dan Le Sac vs Scroobius Pip  Thou Shalt Always Kill

Think a taller version of Eminem, add a beard, more intelligent lyrics, better beats, and, well, forget Eminem altogether. Dan Le Sac is about as urban as this middle-class white boy gets.

Scroobius Pip’s sarcastic vocals came across clearer for Matt on the Realtek codec, and he found the drumming on the Xonars a little dull in comparison. Mo didn’t agree, and thought the ALC892 had an air of static. She liked the DG overall, and preferred its vocals to those of the Xensean opinion shared by me and Cyril. Cyril found the Xense a little timid overall, but we both agreed it and the DG sounded much better than the integrated audio, which sort of mashed things together under a heavy bass line. I quite liked the sound of the Xense overall, but the DG tickled my weakness for a bit of vocal bias.

Nine Inch Nails  Ghosts 14

My favorite track from Nine Inch Nails’ free Ghosts instrumental collection, number 14 is heavy on strings, with a healthy dose of industrial flair.

You learn interesting things while conducting this sort of testing, one of which is that different people listen for different things. Matt, for example, consistently commented that drumming hit harder on the ALC892 than on the rest. Percussion with a little more punch is also the reason he preferred the DG to the Xense with this track. He liked the DG best overall, noting that its background instrumentals were a lot clearer than with the hard-hitting crab.

Indeed, we all preferred the DG with this Ghosts song, and for much of the same reasons, even if we used different words to describe a general sentiment. Mo thought the DG had more range than the Xense, which Cyril said sounded a little muted. I reached the same conclusion from the opposite direction, praising the DG’s brightness versus the Xense, which had more of an even keel.

Radiohead  Weird Fishes_Arpeggit

Another online release, Radiohead’s critically acclaimed In Rainbows spawned this oddly named vehicle for Thom Yorke’s beautifully delicate voice.

Score three for the Xense. Matt found it more vibrant than the DG, which was clearer than the ALC892. Cyril praised the Xense’s natural sound versus the other solutions, whose vocals he found a tad sharp. I detected the same vocal bias, and noted that the DG at least preserved the rest of the spectrum, while the onboard codec made the background instrumentals sound a little compressed. But the Xense was my favorite, as well, thanks to a more even separation between the various elements of the track.

Although she didn’t agree with the rest of us, Mo was at least consistent in picking the DG as her favorite. She did think that all the configs sounded very similar, but also that the Xense was a little tinny when compared to the budget Xonar. The DG, she said, sounded just a bit better than the ALC892.

Tori Amos  Cornflake girl

A little something for the ladies… or I suppose from the lady, Cornflake Girl layers strings, piano, and Amos’ intoxicatingly breathy delivery.

With our final track, the results were nearly split down the middle. Matt and Mo thought the DG sounded better than the others. He detected more separation with the DG than with the Xense and thought the former was clearer than the ALC892, whose drums were too high in the mix. Mo called the differences more subtle, but noted that the Xense’s vocals sounded weak versus the DG. I had similar sentiments, characterizing the DG’s vocals as punchier than those of the pricier Xonar. The DG’s piano stood out a little more for me, too, although the Xense had a more even balance with better separation. Only because I like a little extra kick did I prefer the sound of the DG to the Xense.

Cyril isn’t as easily swayed by a little extra oomph, and he sided with the Xense’s superior separation, even if it sounded just a little bit quieter. The ALC892 didn’t fare as well to his ears, which heard something more metallic and artificial than what was produced by the Xonars. I complained about a blurring in the background with the Realtek codec, and Matt thought it lacked a crispness present in the discrete cards.

Some time has passed since these listening tests were conducted, and I’ve since been able to gather a some additional context that I think will help to explain the results. More often than not, the Xense had the best separation and most even sonic profile of the bunch. It tended to give each element of the track equal attention, and in back-to-back comparisons with implementations that have specific biases, I can see why we often thought the Xense sounded less exciting than its competition. As it turns out, Asus programmed a little extra excitement into the DG. The card isn’t tuned to sound exactly correct, as is the case with the Xense, but to give things like percussion and vocals a little extra pop. And our listeners liked pop. I’m a total sucker for pop, too, especially since it often amplifies my favorite elements of a given song.

The ALC892 has some extra kick of its own, but not like the DG. Here, the question isn’t whether there’s bias, but what, if anything, that bias costs you. On the DG, I’m left with the impression that that Asus has nudged up the volume on a couple of instruments without messing with the rest of the band. With the Realtek codec, it sounds like the drums and vocals have been turned way up, robbing focus and bandwidth from the rest of the spectrum. Both solutions are guilty of massaging the sound a little before passing it to your ears, but the DG’s touch doesn’t disturb the surroundings, while the onboard audio can trample on background instrumentals and other subtleties.

RightMark Audio Analyzer – 16-bit/44.1kHz

Moving from subjective listening tests to something more objective, we used RightMark Audio Analyzer to evaluate output quality. We gathered these results with “loopback” tests that route a sound card’s output through its line input. We’ll kick things off with 16-bit/44.1kHz CD-quality 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.

Since the Xense has two effective front-channel outputs, one for speakers and another dedicated jack just for headphones, we tested both. The DG and our test system’s motherboard lack dedicated headphone ports, so we limited our loopback tests to their front-channel outs.

RightMark Audio Analyzer audio quality – 16-bit/44.1kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC892 5 4 4 3 1 3 5 3 4 Xonar DG 5 6 6 5 4 6 6 6 5 Xonar Xense (Front) 6 6 6 6 5 6 6 6 6 Xonar Xense (Headphone) 6 5 5 6 4 6 6 6 6

The Xense edges out the DG in the battle of the Xonars, scoring higher in only a couple of the tests. Both stay ahead of the Realtek codec, which to be fair, is only one point behind in the overall score. However, the ALC892 also has lower scores across the board.

If you want to geek out over a bunch of detailed RMAA graphs, we’ve provided the raw results for all of our RMAA tests below. You don’t have to look over them all, but here are a few things to look for. First, check out the plot of frequency response, which we’ve put first on this and the following pages. The Xense flat-lines acroess the entire spectrum, while the DG and ALC892 each drop off earlythe Realtek considerably more dramatically than the Xonar. Also telling is the noise-level graph, which tracks the noise you don’t want in the signal.

Surprisingly, at least based on the results of our listening tests, the Xense’s headphone output tracks closely with the ALC892 in a number of RMAA plots. However, the latter spikes much more frequently than any of the discrete sound cards in the total harmonic distortion and intermodulation distortion graphs.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

RightMark Audio Analyzer – 24-bit/96kHz

RightMark Audio Analyzer audio quality – 24-bit/96kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC892 5 4 4 5 3 4 5 4 4 Xonar DG 6 6 6 5 4 6 6 6 5 Xonar Xense (Front) 6 6 6 6 6 6 6 6 6 Xonar Xense (Headphone) 6 6 6 6 5 6 6 6 6

The scores are nearly identical with 24-bit/96kHz audio. Once again, the Xense comes out on top. The DG remains competitive with its costlier cousin, and it’s well ahead of the Realtek codec.

Before scrolling down to the next page, let your eyes linger a little on that plot of frequency response. As we kick up the audio quality, the Realtek codec struggles even more to keep up with the Xonars.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

RightMark Audio Analyzer – 24-bit/192kHz

RightMark Audio Analyzer audio quality – 24-bit/192kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Realtek ALC892 5 4 4 5 3 5 5 5 5 Xonar Xense (Front) 6 6 6 6 6 6 6 6 6 Xonar Xense (Headphone) 6 6 6 6 5 6 6 6 6

The DG’s lack of support for 192kHz sampling rates relegates it to the bench for this testnot that the Xense needs much help defending the honor of discrete sound cards. Both of its output paths score higher than the ALC892, which bounces back after turning in lower scores at 96kHz.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk

Extra credit – RMAA after an OPAMP swap

Curious to see whether my ears or RightMark Audio Analyzer could tell the difference between the Xense’s stock OPAMPs and the ones sold in Asus’ upgrade kit, I did a swap and ran some tests. Mostly, this was an excuse to take a picture of something really small with my new Canon EOS Rebel T2i camera. So, here you go:

Yeah, I’m still working out the kinks. But my, what a nice pair of National Semiconductor 49720NAs. How do they fare against the card’s default JRC 2114D amplifiers?

RightMark Audio Analyzer audio quality – 24-bit/192kHz Frequency response Noise level Dynamic range THD THD + Noise IMD + Noise Stereo Crosstalk IMD at 10kHz Overall score Xonar Xense (JRC 2114D) 6 6 6 6 5 6 6 6 6 Xonar Xense (LME 49720NA) 6 6 6 6 5 6 6 6 6

Nearly identically, at least according to RMAA. Even our fancy plots show the two OPAMPs right on top of each other. My ears couldn’t tell the difference with headphones, either. To be fair, though, I wasn’t able to do much of a back-to-back listening test to tease out subtle differences. Swapping OPAMPs is a pretty quick task, but it does take a few minutes, especially since I wanted to have the shielding in place during playback in case it affected the results.

Frequency response

Noise level

Dynamic range

Total harmonic distortion + noise

Intermodulation distortion

Stereo crosstalk