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Review and Measurements of Asus Xonar U7 MKII ADC/DAC/HP

amirm

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#1
This is a review and measurements of the Asus Xonar U7 MK II multi-channel DAC, Headphone Amplifier and Analog to Digital (ADC) converter. A member overseas prompted me to purchase this unit to test by donating to the forum nickel jar. :) At just US 90 on Amazon with prime shipping, this is quite a bargain if it lives up to its specifications.

From the outside, the U7 leaves a very positive impression:

Asus Xonar U7 MK II Audio Review.jpg

There is somewhat nice feeling rotary control for volume control. Alas, it is just changes the PC/Windows volume level so don't expect it to have good resolution. It is clickable and selects between "speaker" (really line out) and headphone out. There is also a S/PDIF out but only controllable through their app.

The back panel shows the connectivity and continued good looks:

Asus Xonar U7 MK II Back Panel Audio Review.jpg

Overall the hardware leaves a very good impression despite the plastic housing and such. Sticky feet keep the unit planted nicely as you use it.

I plugged the unit in and to my disappointment, ASIO4ALL wrapper I use with my analyzer hardware could not control it. It would see it but could not output anything. So I fired up my Roon player and it worked fine using WASAPI.

To fix the ASIO4ALL issue, I downloaded the Asus crapware which clocked at whopping 120 megabytes. Installation worked fine and a fancy control panel popped up. Also "nice" was the ASIO driver which was also installed. Sadly, as soon as I would try to use that ASIO interface, my Audio Precision software would lock up solid. For some reason though, ASIO4ALL started to work.

Unfortunately once you install the driver/app package the device shrinks its reported formats to to just 16 bit and 44.1 and 48 kHz. This is what it looks like in Windows sound properties and their own app. Whoever wrote this software package/driver needs to get a different job as it sure ruined an otherwise nice hardware experience.

DAC Measurements
Playing my 24-bit, 1 kHz tone file using Roon produced very nice performance for a budget PC sound interface:

Asus Xonar U7 MK II RCA Audio Measurements.png


Output level is low so if you have powered speakers, you may not be able to get maximum juice out of them. I like to see 2 volt output.

Specifications for SINAD (signal over noise and distortion) is essentially met as they use a-weighting which improves things a bit. That puts the U7 MKII in competent bucket of DACs tested:
Asus Xonar U7 MK II RCA With Driver SINAD Audio Measurements.png


Sadly, as soon as I installed the crapware package, as I mentioned above, we lose 24 bit performance and with it, 10 dB of SINAD:

Asus Xonar U7 MK II RCA With Driver Audio Measurements.png


Going with this anyway, I ran a few more tests:

Asus Xonar U7 MK II RCA With Driver Linearity Audio Measurements.png


We not only not have 24 bit support, but also see truncation of 24 bit samples to 16, causing that zigzag error.

Frequency response is fine:
Asus Xonar U7 MK II RCA With Driver Frequency Response Audio Measurements.png


SNR is impacted by the 16 bit truncation I think:
Asus Xonar U7 MK II RCA With Driver Dynamic Range Audio Measurements.png


We are capped to the classic limit of 96 dB for 16 bit data.

Jitter test doesn't show jitter but side effect of truncation to 16 bits:
Asus Xonar U7 MK II RCA With Driver Jitter Audio Measurements.png


Headphone Amplifier Measurements
Here is the performance with 300 ohm load:
Asus Xonar U7 MK II RCA With Driver Audio Headphone 300 Measurements.png


Very depressing. 5 milliwatts? That is nothing. A phone can have higher output.

Story doesn't get better with 33 ohm load:

Asus Xonar U7 MK II RCA With Driver Audio Headphone 33 Measurements.png


To add insult to injury, output impedance is a high, 22 ohm:
Best Headphone Amplifier Output Impedance Measured.png


Clearly this is a checklist item, not a serious attempt at any kind of proper headphone amplifier.

ADC Audio Measurements
Just in case you want to use a microphone with this device or for digitizing your LP library, here is how it performs its digitization duties:
Asus Xonar U7 MK II RCA With Driver ADC Audio Measurements.png


As with output, input is limited to just 1 volt before reaching saturation (0 dBFS). Distortion is quite high causing SINAD to be unimpressive at average of 86 dB:

Best ADC Audio Interfaces Reviewed 2019.png


This is well under the specification of 100 dB even though theirs is a-weighted. Likely the 16 bit issue is biting us here too.

But hey, we are doing better than Behringer UMC204 HD.

Frequency response is ruler flat which is excellent:

Asus Xonar U7 MK II RCA With Driver ADC Frequency Response Audio Measurements.png


Linearity shows classic problem of truncation just as well in capture mode:
Asus Xonar U7 MK II RCA With Driver ADC Linearity Audio Measurements.png


Conclusions
Seems like a real engineer was put on this project to design the hardware and mechanical/industrial design. They deserve a high grade. Alas, a rookie software engineer was put to the task of writing the driver and likely used some old code that assumed the device is only 16 bits and at 44.1 and 48 kHz, marketing specs of 24 bit/192 kHz be damned. Whoever tested the system as a whole didn't know much about this either, and let this flaw get through.

If you are just going to use this device for music and don't have a need for their processing, then you are good without the driver install. You will have a DAC that has better performance than likely what is on the motherboard. Sadly the headphone output is junk so you are going to have to get an external box to get good performance there.

The ADC is good enough for microphone use and such.

The Asus Xonar U7 MK II comes close to getting my vote of confidence but typically of PC sound card vendors, falls flat on the software/testing side. What a shame. Hopefully they hear about this review and revise the software to fix. If so, they will have a hit on their hands with respect to a multichannel DAC.

------------
As always, questions, comments, recommendations, etc. are welcome.

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amirm

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#3
It is as if they are all follow the same road into a ditch.

They cost me so much time in trying things to get the darn thing to work. :( I spent 3X more time on these products that don't work like they are supposed to.....
 

JohnYang1997

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#4
My u7 (not mkii) having no trouble running in 24bit. Just select in the interface. And my friedns had no problems running in 24bit with their u7mkii. I know it's frustrating, but i think it's doable.
 

Arnandsway

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#5
How could this device be optimally used? If some users could share suggestions, that would be great!
It's also weird that only two-channels show up, and not the 7.1 channels. If it would, a cheap MCH-dac would be at hand. :)
 

Tks

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#6
Why are so much audio software/driver packages written my literal monkeys :oops: the moment you see 16-bit truncation for no reason you know it's another fail.

Thanks for the review, @amirm.
It's one of those unspoken mysteries of the world, how multi million/billion dollar companies make such idiotic and almost unbelievable fumbles.
 
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#7
Maybe if you slice off the top bits you get that nice bit-crushed sound like those old 12-bit samplers. /s

Seems like bad conversion to 16-bit should be unacceptable these days when open-source resampler libraries like SoX exist, but truncation is on a whole different level.
 

pwjazz

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#8
Not that I need AD conversion, but at a similar price a Focusrite Scarlett Solo seems to provide better features and good stated specs.
 

JohnYang1997

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#9
Maybe if you slice off the top bits you get that nice bit-crushed sound like those old 12-bit samplers. /s

Seems like bad conversion to 16-bit should be unacceptable these days when open-source resampler libraries like SoX exist, but truncation is on a whole different level.
I think it's just settings. People had no issues using them as cheap measurement equipment. very good distortion at low level.
 
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#11
I mean it's asus, they also make great Motherboards with buggy BIOSes. Not surprised at all they have people who know how to layout a circuit like this but then screw it up with software.
 

IVX

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#12
I have the same one($80 in China), ADC and its frontend deeply modified(CS5361 to CS5381, fully differential input OPA1612, SNR -119.4dbA + 600:600 trafos and +/- 7VDC power rails). I didn't measure DR AES17 but SNR was really -115dbA at RCA outputs, very strange that DR is so low(looks like THD about 1% at -60db level, too hard to believe). Usually, the reason is USB HF current-loop related noise etc, anyway better to check DR with battery-powered laptop or AUX0025 to reduce HF disturbance, AP27** were always too sensitive to that.
 

JohnYang1997

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#13
I have the same one($80 in China), ADC and its frontend deeply modified(CS5361 to CS5381, fully differential input OPA1612, SNR -119.4dbA + 600:600 trafos and +/- 7VDC power rails). I didn't measure DR AES17 but SNR was really -115dbA at RCA outputs, very strange that DR is so low(looks like THD about 1% at -60db level, too hard to believe). Usually, the reason is USB HF current-loop related noise etc, anyway better to check DR with battery-powered laptop or AUX0025 to reduce HF disturbance, AP27** were always too sensitive to that.
I got 0.0002% at -20dbfs.
 

Cosmik

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#14
I've been using this as my multichannel DAC for the last three or four years. It seems to work fine with Linux under Alsa (I disable Pulseaudio), but there is one tweak you need to do to fix a 'Broken Pipe' error. That's Linux for you.
 
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#15
Thanks for the review @amirm but may I ask you to please measure any of the other output channels (surrounds or center/sub)? I am curious to know if these are at least well engineered besides the driver fiasco. I use a PCI-E audio card from Asus (with non standard drivers) to run my 5.1 setup and maybe this way I can figure out how these other channels perfome.
 

graz_lag

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#16
No magic or surprise here, the device has been designed for PC gaming around a $5 chip (Cirrus Logic CS4398) as DAC.
It comes with some sound utilities by ASUS as the Sonic Studio software interface as well as the Sonic Radar Pro, which are pretty much liked by the PC gamers.
The price has dropped down to 60 EUR or so, here in France recently, so it offers a very good value for money as multi-channel USB preamp for PC gaming applications.
 
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#18
Regarding driver issues - I wonder if the software devs. are having issues writing drivers for Windows 10?
Also @amirm - it's often possible to just install the drivers without installing all the associated crapware. I've done it a few times with my Asus Xonar STX.
I see the U7 is retailing at £71 here in the UK, and that's on Prime too.
I had considered getting one of these to use in place of my Asus Xonar STX and Focusrite Scarlett 2i2, but I see I'd be wasting my time.. (i use them for audio measurements and little else).
 

BYRTT

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#19
...trying things to get the darn thing to work...
Have the none MKII unit laying around somewhere and it had worked fine if one stay away of their latest driver package release called "Sonic Studio" which strangely enogh adds 3 times 360º phaseshift to Windows sound system driver as was it a summed 3 way 4th order minimum phase XO filter, ASIO is clean for that "Sonic Studio" package but better to use the latest driver that is not named "Sonic Studio.

That said both U7 and U7 MKII have a micro switch at the bottom of unit as seen below and suggest give it a try if that switch is accidently set set in 1.0 mode :)

1040.png
 

amirm

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#20
Regarding driver issues - I wonder if the software devs. are having issues writing drivers for Windows 10?
Could be. Microsoft seems to be messing with the sound subsystem lately given the new control panel and such.

Also @amirm - it's often possible to just install the drivers without installing all the associated crapware. I've done it a few times with my Asus Xonar STX.
There is only one .exe download link unfortunately. So no way to just get the driver. I think the driver is the problem anyway as Windows also thinks post installation that it only supports 16 bit at 44.1/48kHz.
 
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