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:
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:
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:
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:
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:
Going with this anyway, I ran a few more tests:
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:
SNR is impacted by the 16 bit truncation I think:
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:
Headphone Amplifier Measurements
Here is the performance with 300 ohm load:
Very depressing. 5 milliwatts? That is nothing. A phone can have higher output.
Story doesn't get better with 33 ohm load:
To add insult to injury, output impedance is a high, 22 ohm:
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:
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:
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:
Linearity shows classic problem of truncation just as well in capture mode:
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.
Apparently the "pink" panthers are tired of dressing in pink all the time and are asking me to paint them a different color. Having no skills in painting, nor any supplies, I need some money to take lessons and buy the paints. Please donate using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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:
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:
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:
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:
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:
Going with this anyway, I ran a few more tests:
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:
SNR is impacted by the 16 bit truncation I think:
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:
Headphone Amplifier Measurements
Here is the performance with 300 ohm load:
Very depressing. 5 milliwatts? That is nothing. A phone can have higher output.
Story doesn't get better with 33 ohm load:
To add insult to injury, output impedance is a high, 22 ohm:
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:
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:
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:
Linearity shows classic problem of truncation just as well in capture mode:
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.
Apparently the "pink" panthers are tired of dressing in pink all the time and are asking me to paint them a different color. Having no skills in painting, nor any supplies, I need some money to take lessons and buy the paints. Please donate using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
