ASUS Xonar U3 USB Audio Card Review

Author: Carl Poirier
Editor: Howard Ha
Publish Date: Tuesday, August 7th, 2012
Originally Published on Neoseeker (
Article Link:
Copyright Neo Era Media, Inc. - please do not redistribute or use for commercial purposes.

It's generally accepted that onboard audio cards have gotten much better over these past few years. It was more common before to see dedicated audio cards being installed in computers, but now such components are becoming more of a niche market. There are still many systems that feature cheap soundcards though, for example netbooks. Granted, even then there are a few models that have better stuff such as Harman Kardon speakers, but they are scarce.

With a good pair of headphones, it becomes evident that these systems are lackluster in sound quality. Not only that, but the feature set is much more limited or even non-existent. ASUS has a product that remedies this: the very small USB audio card named the Xonar U3.


Audio Performance Output Signal-to-Noise Ratio (A-Weighted) (Front-out):
100 dB
Output THD+N at 1kHz (Front-out) :
<0.005 %( dB)
Frequency Response (-3dB, 16bit/48KHz input):
20 Hz to 20 KHz
Output/Input Full-Scale Voltage
2Vrms (5.65Vp-p
Bus Compatibility USB
Main Chipset Audio Processor: ASUS UA100 USB Audio Chip
Sample Rate and Resolution Analog Playback Sample Rate and Resolution :
48KHz @ 16bit
I/O Ports Analog Output Jack:
1 x 3.5mm RCA jack
Analog Input Jack:
1 x 3.5mm RCA jack
1 x 3.5mm Digital S/PDIF Output
Special Features Dolby® Digital Live / Dolby® Headphone / Dolby® Virtual Speaker / Dolby® Pro-Logic II
Smart Volume Normalizer™
Xear 3D™ Virtual Speaker Shifter
Magic Voice™
Karaoke Functions
10 -band Equalizer
27 Environment Effects
GX2.5 Gaming Audio Engine
Accessories 1 x S/PDIF optical adaptors
1 x Driver CD
1 x Quick Start Guide
1 x 30cm USB Extension Cable
Dimensions 79.5 x 30.6 mm (L x W)

Specifications are courtesy of ASUS @

Does the Xonar U3 have speakers hiding behind these two meshes? One could think yes at first glance, but in fact there was no mention of speakers in the specifications listed on the previous page. The rest of the U3 body is a glossy black plastic that is prone to collecting fingerprints. If hung on a key ring by its cord, it won't take long before the U3 gets scratched all over by the diverse metal parts found in one's pocket. The text is printed on the body in such a way that one can actually feel them, leaving the impression they can easily be scratched off.

Opening up the cover reveals the USB port, which gives a better idea of the size of the U3. It's definitely small, but still way too big to fit beside other devices which might also be plugged into the same IO panel. ASUS has a remedy for this in the form of a small USB extension cable, shown later.

On the other end of the U3 are two standard 1.8mm analog audio jacks, one input and one output. The connector on the left can also serve as an optical output if used in conjunction with the supplied TOSLINK.

Plugging the U3 into to a running system reveals that behind the two meshes mentioned earlier are merely blue LEDs indicating when the unit is powered.

The bundled accessories include the aforementioned USB extension cord and TOSLINK adapter.

Test Setup


Comparison components



The Xonar U3 and the comparison cards will be run through the usual audio benchmarking gauntlet which consists of listening to various sources to compare the sound quality. Comparisons are easier to make with cards that can run alongside one another in the same PC (unlike two ASUS Xonar cards) because switching between them merely consists of changing audio jacks; the OS takes care of switching the output device and the music continues. The card's equalizers are left at default settings.

Before beginning, it's also important to mention that the card is supported by ALSA. ASUS has at least made a device that works with the generic USB soundcard driver.


Listening to some personal favorites such as Jesse Cook, Alan Jackson, Deadmau5 and Mario Bros., not much difference is noticed between the U3 and the Realtek ALC892 audio. In some cases, the latter exhibits a tiny bit clearer bass, and that's depending on the track playing. Besides that, it is pretty tough to discern one from the other. One sure thing though is that the U3 does not lack any power to drive higher impedance headphones, thanks to its integrated amplifier.

One key area where the ASUS offering performs better is the karaoke function. In fact, it works more often than the Realtek implementation. That's not to say it works well all the time though, as in most songs it's still complete garbage; the frequency response is so modified that one's first reaction is "wtf", but for a few select artists such as Alan Jackson, it's decent enough to use it during a family holiday party.

The U3 also a Dolby Headphones feature not available on the Realtek card (to keep the cost down as it is a licensed technology) which some listeners might appreciate.

Movies and Gaming

The most important aspect for gaming audio is a good spatial representation. The U3 can effectively output up to 7.1 audio via its optical link. It's a nice bonus if the U3 is plugged in a sound system with such a capability, and that system is most probably going to feature a better digital to analog converter, too. When it comes to laptops, models with an optical audio out are more rare so the U3 has a very clever use in that market; allowing the system to send surround audio to a receiver. If limited to simulating such a speaker setup via its 2-channel analog output however, then the U3 is not really worth it over a simple stereo configuration.

For communication, be it in-game or a VoIP application, the Xonar U3 has another trick in its bag: the VocalFX technology. It simply allows the user to modify their voice to hide his/her identity (or just for the heck of it).

Rightmark Audio Analyzer is a sound card benchmark. It works by playing sounds and recording them back using a loopback audio cable. It then analyzes the recording and deduces the audio properties of the soundcard. 


Test ASUS Xonar U3 Realtek ALC892 Realtek ALC889
Freq. Response
(40Hz-15kHz), dB
+0.32, -0.44 +0.05, -0.01 +0.07, -0.14
Noise level, dB (A) -76.4 -80.1 -74.0
Dyn. Range, dB (A) 74.9 80.2 73.4
THD, % 0.105 0.0063 0.130
IMD + Noise, % 0.222 0.031 0.262
Stereo Crosstalk, dB -74.9 -77.2 -71.3


Frequency Response

Noise Level

Dynamic Range

THD + Noise (at -3DB FS)

Intermodulation Distortion

Stereo Crosstalk


The Xonar U3 loses heavily against the top onboard/integrated audio offerings from Realtek; the frequency response is not uniform at all, the noise is much higher, the dynamic range is not as large,  the harmonic distortion is also much higher, there is more intermodulation distortion, and more stereo crosstalk. In fact, the U3 is more on the caliber of the Realtek ALC889. Given that integrated audio on motherboards comes at no cost to available space for the user, the U3 was expected to perform better than the ALC889 despite its size for a USB device.

Overall, the ASUS Xonar U3 is not really impressive by any means, but it has its uses. It can add an optical audio output to a system that doesn't have one, such as a laptop. It has some features not normally found on integrated audio too; Dolby Headphones applies an algorithm to the output that makes it sound more ambient, and VocalFX allows one to modify his voice for a variety of purposes.

Performance wise, the Xonar U3 proved to be far inferior to the Realtek ALC892 in all tests, and closer to the ALC889. Their perceived sound quality was similar, too, sometimes a tiny bit clearer on the top stuff from Realtek. Strictly in terms of performance, the U3 is not really much of an upgrade compared to onboard audio. It definitely fares well against the integrated stuff in netbooks, though.

The U3 could also be improved in physical design. It's made to be portable, yet its glossy exterior will most probably be scratched quite easily if put with other objects in the same pocket. A rugged finish like the one found on many USB keys would have been more appropriate. There are also the two speaker-like meshes that don't really have any purpose other than to light up; a smaller LED in the corner would have worked just as well yet offer a more classy look.

At $30 after rebate, this portable Xonar is actually quite affordable, so buying it for reasons outside of sheer audio quality would be understandable.


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