Sound cards are some of the most overlooked components when doing a system upgrade as many people believe that decent speakers or headphones will sound good regardless of the source. This is true to an extent, but once you start moving away from entry level equipment you’ll quickly find yourself held back by onboard audio. This is an even bigger issue if you’re using a laptop, as laptops generally have poorer audio CODECs than desktop motherboards.
The ASUS Xonar U7 is designed with this specific need in mind, being a USB sound card and headphone amplifier for laptops, netbooks and ultrabooks. Of course, there is nothing stopping you from using the device with a desktop PC. It would be a great companion to an HTPC, which might not have enough expansion slots for a TV capture card, graphics card AND sound card. ASUS have managed to do away with the need for an external power supply, drawing all required power directly from the USB port.
As the front of the box shows, the ASUS Xonar U7 is a 7.1 channel surround sound USB sound card and headphone amplifier supporting Dolby Home Theater v4, 192 KHz 24 bit audio and up to 114 dB SNR (signal to noise ratio). The flip-open cover reveals the device itself, as well as a brief description of the capabilities. Special mention is made of the Cirrus Logic CS4398 DAC, the same DAC seen on sound cards such as the Creative Sound Blaster Z and ASUS Xonar D1/DX.
The back of the box goes into further detail of the Xonar U7′s capabilities, giving a short rundown on what the buttons do, which output is which and the package contents. ASUS shows the Xonar U7 to offer an SNR of up to 114 dB, which is slightly lower than the 116 dB offered by many internal sound cards but still very impressive for a USB device.
For those who can’t see, the side of the box has the following information:
- Signal-to-Noise Ratio (SNR): 114 dB
- THD+N @ 1KHz (-3 dB): Up to 0.0006% (104 dB)
- Frequency Response: 10 Hz to 46 KHz
- Sample Rate and Resolution: Up to 192 KHz @ 16/24 bit
- Bus Compatibility
- USB audio class 2.0 for all functions
- USB audio class 1.0 for playback
- Power Supply: USB-powered
- Headphone Amplifier (impedance): 32-150 ohm
Inside the box you find split packaging, with the Xonar U7 itself at the top. Digging deeper down, you’ll find a driver disk, 1.5 meter USB cable, thick instruction manual and an S/PDIF TOSLINK optical converter. Most people can safely skip by the manual, as if you can figure out how to take the manual out of the box you can figure out most of what is covered.
The front of the Xonar U7 has a stereo headphone output, microphone input and microphone volume controls. On top of the unit is a large volume dial which also doubles up as an output source button when pushed. Three blue LEDs show the currently selected output: one each for headphones, speakers and S/PDIF.
The speaker outputs are aligned along the back of the unit – two RCA jacks are present for the left and right front channels, while the center, side and rear speakers have a 3.5 mm stereo jack each. A possible oversight on ASUS’ behalf is the lack of RCA-to-3.5 mm converters, as if you want to use a surround sound speaker set which uses three 3.5 mm jacks you’ll have to purchase extra cables. The S/PDIF jack and USB port for interfacing with the computer are located just after the 3.5 mm connectors.
The bottom of the Xonar U7 has a small slider switch which allows you to change between USB 1.0 and USB 2.0 mode. In USB 1.0 mode, the unit only supports basic playback features and limits audio quality to 44.1/48 KHz at 16 bit. Although the manual says that USB 2.0 mode is for Mac OS X, it works perfectly on Windows-based operating systems and is required for the advanced functionality.
The Xonar U7 uses something ASUS calls Hyper Grounding technology, which keeps the analog and digital layers separated by two ground layers in order to reduce interference. The unit uses the C-Media 6632 audio processor which supports up to three input and output streams as well as ASIO 2.2 (Steinberg Audio Streaming Input Output). As mentioned earlier, ASUS have given the Xonar U7 the same Cirrus Logic CS4398 stereo DAC seen in their high-end desktop sound cards, as well as a multi-channel Cirrus Logic CS4362. Lastly, it uses the Cirrus Logic CS5361 ADC. The headphone output is amplified, and can certainly push a lot of volume.
The Xonar U7 control panel allows you to select environmental emulation effects, volume, virtual headphone surround sound settings and similar. The Dolby pop-up system tray applet lets you quickly choose between seven equalizer settings, while the Dolby control panel allows for custom sound profiles and offers a graphic equalizer. The software almost feels too basic even though it offers all of the settings you could possibly need.
The Xonar U7 was tested our usual dual CPU rig which has had a few minor changes. The specs are as follows:
- 2x Xeon E5645
- EVGA Classified SR-2
- 48 GB Patriot G.Series
- PowerColor Radeon HD 7970
- be quiet! Dark Power Pro 10 1200W PSU
- Intel 320 Series 120 GB SSD
- Windows 7 64-bit
We compared the Xonar U7 to the EVGA motherboard’s integrated Realtek audio CODEC using RightMark Audio Analyzer, as well as some real-world use with three sets of headphones – the cheap and nasty Genius Headset HS-04A, the slightly higher end iFrogz EarPollution Ronin (7067-ERMN), and the high-end M-Audio Studiophile Q40. RightMark Audio Analyzer isn’t completely accurate, but can be used to give a good idea of the performance in relation to the onboard sound. Here are the results:
- Frequency response (from 40 Hz to 15 kHz), dB
- Realtek: +0.14, -0.42
- ASUS Xonar U7: +4.63, -3.63
- Noise level, dB (A)
- Realtek: -74.1
- ASUS Xonar U7: -94.7
- Dynamic range, dB (A)
- Realtek: 73.2
- ASUS Xonar U7: 91.0
- Total Harmonic Distortion, %
- Realtek: 0.014
- ASUS Xonar U7: 0.0055
- Intermodulation Distortion + Noise, %
- Realtek: 0.088
- ASUS Xonar U7: 0.068
- Stereo crosstalk, dB
- Realtek: -68.9
- ASUS Xonar U7: -90.5
- Interodulation Distortion at 10 kHz, %
- Realtek: 0.086
- ASUS Xonar U7: 0.015
The paper results are very good for the price you pay for the Xonar U7, but of course sound quality is not something that can be measured in numbers alone. After spending some time listening to various genres of music in FLAC (a lossless format), covering everything from Black Sabbath to Enya and many in between, the difference is quite vast. The music changes from stereo to something more three-dimensional, as if it isn’t coming FROM the headphones but rather OUT OF them.
Of course, a decent set of headphones is a requirement. With the Genius Headset HS-04A it was impossible to tell any difference, indeed it was difficult just to tell the difference between a mid-quality MP3 and FLAC. With the Earpollution headset there was a fairly pronounced difference, with the sound-stage widening and the bass-lines becoming more distinct. It was only with the M-Audio Q40s that the Xonar could show its true colors, completely changing the immersive effect. It no longer sounded like a pair of headphones, but rather that you were right there in the studio while the music was being recorded.
In the end, the ASUS Xonar U7 scored as follows:
While the ASUS Xonar U7 is not an alternative to a high-end PCI or PCI-Express sound card, it’s a brilliant option for those who cannot use an internal card. Laptop users with decent headphones are doing themselves an injustice by using onboard graphics when the Xonar U7 has the ability to completely transform the listening experience. The Xonar U7 should hit retail soon and is expected to be priced around US $100. Jonathan Horne