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Add-on integrated audio
Digital audio outputs tend to deliver crystal clear sound quality regardless of whether they're attached to discrete sound cards or integrated motherboard solutions. Analog sound quality is typically much better on discrete sound cards than in onboard implementations, though. Stand-alone cards can dedicate more board real estate and components to their audio circuitry. They also elevate everything off the surface of the motherboard, separating sensitive analog signals from potential sources of interference.

Mini-ITX boards have only one full-sized expansion slot, forcing users to choose between discrete graphics and sound cards. Audio usually ends up on the losing end of that battle, and the Maximus VI Impact doesn't change that dynamic. However, the board does elevate its integrated audio to another level via the SupremeFX riser card.

This mini sound module is a sort of cross between the discrete and integrated approaches. It uses a Realtek ALC1150 codec familiar from traditional motherboard audio configs. The chip sits on a riser card instead of the motherboard, though, separating it from board-level noise. The codec is also covered by a separate EMI shield that provides an additional layer of protection.

In a bid to further improve sound quality, the SupremeFX module employs a "dual-differential" circuit design that splits audio signals from the codec into two separate streams. The second stream is the inverse of the first, and the two are recombined by amplifier chips using a process that's supposed to filter out noise and interference. There are four Texas Instruments LM4562 amplifiers on the riser: three for the analog jacks at the rear, plus one more for the front-panel headphone connector. These amps are rated for headphones up to 600 Ω, which covers most common audio headgear.

Asus claims the SupremeFX riser has a signal-to-noise ratio of 115 dB for the rear outputs and 110 dB for the front headphone jack. Those figures seem impressive, but they reveal little about how the audio actually sounds. To get a better sense of that, I spent an afternoon listening to music on the Impact and a couple of alternatives: the more traditional integrated audio offered by Asus' X79 Deluxe ATX motherboard and our favorite discrete solution, Asus' Xonar DSX sound card. These tests were conducted with the rear analog outputs, Sennheiser HD 555 headphones, and normalized volume levels. The playlist included tracks from Adele, Die Antwoord, The Heavy, LCD Soundsystem, and The Tea Party.

To my ears, the Maximus VI Impact's integrated audio sounds noticeably better than that of the X79 Deluxe. The highs are crisper, the bass is smoother, and the individual elements of each track come through more clearly. Foreground elements pack a harder punch than they do on the Deluxe, and subtler notes don't get lost in the background. The difference isn't night and day, but all the little improvements add up to produce a livelier, more detailed sound than typical motherboard audio.

Although the Impact's SupremeFX audio is a definite improvement over the integrated norm, it's not on the same level as a good discrete sound card. The Xonar DSX exposes even more subtlety in each track. It has greater range in the middle of the spectrum and a more balanced acoustic profile overall. The Xonar also boasts a more natural sound, without the over-sharpened highs and over-emphasized bass that creeps into the Impact's output.

For me, the difference between the Xonar and the Impact is bigger than the delta between the two integrated solutions. The Impact still offers an enjoyable listening experience, though. It definitely has better analog output quality than any other Mini-ITX board I've tested.

In addition to evaluating audio performance with subjective listening tests, we measured signal quality objectively using RightMark Audio Analyzer. We ran the same three audio implementations through RMAA's "loopback" test, which pipes audio from the front-channel output through the line input. This test was configured to use high-definition audio with 24 bits of resolution at 96kHz. RMAA ranks subjects in a range of categories using a six-point scale between "very poor" and "excellent." We've converted those results to a numerical scale between a low of one and a high of six.

Frequency
response
Noise
level
Dynamic
range
THD
distortion
THD +
noise
IMD +
noise
Stereo
crosstalk
IMD at
10kHz
Overall
score
Maximus VI Impact 5 6 6 5 3 4 6 5 5
X79 Deluxe 6 5 5 5 4 5 6 5 5
Xonar DSX 6 6 6 6 6 6 6 6 6

Surprisingly, the X79 Deluxe outscores the Maximus VI Impact in a few RMAA metrics. The two boards have the same overall rating, though. Both are beaten soundly by the Xonar, which ranks as "excellent" across the board.

We can get a better sense of how the Impact measures up by examining the raw RMAA data. Here are some comparison graphs for several key RMAA metrics. Click the buttons below to switch between them.


The Impact clearly has a narrower frequency response than the Xonar. It also exhibits more crosstalk, noise, and interference than the DSX across the full range of frequencies. Decent discrete sound cards are really in another league.

Versus the X79 Deluxe, the Impact looks a little better. The SupremeFX signal has less noise and interference across most of the spectrum, though it doesn't fall off like the Deluxe does at extremely high frequencies. That drop-off may be responsible for the Deluxe's higher scores on our numerical scale.

The RMAA results above were obtained with the systems idling at the Windows desktop. We also ran the same tests while the machines were crunching a combined CPU, GPU, and USB load. RMAA didn't detect any differences in signal quality, and I didn't hear any feedback or buzzing in the line.

We're not done with the integrated audio yet. The Impact has a couple of other tricks up its sleeve, including the ability to pass signals from the front-panel input to the rear output when the system is turned off. Then there's Sonic Radar, an Asus-developed application that provides a visual representation of surround-sound game audio. Allow me to illustrate:

The overlay on the gun is the Sonic Radar display. It's highly configurable, with adjustable opacity, size, and positioning. There are different filtering modes, too, allowing one to focus on specific kinds of sounds or all those deemed as threats. These settings can be altered not only through the configuration utility, but also via hotkeys.

Sonic Radar works surprisingly well. The visual display accurately maps in-game audio with no apparent latency. However, I don't find it terribly useful, mostly because looking at the overlay distracts from the action. For me, listening for audible cues is much easier. The software is optional, of course, so you don't have to use it.

Speaking of optional, let's move on to the Impact's second add-on module...