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

Rollinnn

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What maximum frequency is really supported and working in multichannel modes (5.1 and 7.1)?
 

DamonLynch

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Just extracted the drivers. Hope this helps:

https://www.dropbox.com/sh/jta6t3kerxtqtml/AAActXVZWdp1VtU0KlzT0KBza

Edit: From Asus Xonar U7 MKII driver version 1.1.17 dated 2017/07/19.

Thanks very much for taking the time to do this! It fixes an issue with the standard Windows driver. With the standard driver, when you switch output between headphones and speakers, the output volume remains constant. Maybe some people like that, but for this device I don't think it makes much sense. The speaker volume is anaemic, but for 64 ohm headphones at least, at the same setting the volume is deafening. For a setup like this, it's obviously better to have a different output volume for headphones and speakers, which is what you get with the Asus driver.
 

JohnYang1997

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You should be able to change gain setting in the control panel of normal driver.
 

trl

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Immersed

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I have the U7 MKII, you're much better off not installing the Asus software just let Win 10 install a driver. The only functionality you lose is the mic volume button.

Surprised at the low headphone output, I can hear no difference between the U7 II, a JDS Atom, onboard Realtek or onboard from a Surface 3 using HD600 HPs.

Perhaps the need for a HP amp is exaggerated.
 

trl

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Perhaps the need for a HP amp is exaggerated.
For easy-to-drive headphones a dedicated headamp is probably not needed, indeed, like Audio Technica ATH-M30X that has a high sensitivity and a 47 Ohms impedance.

When you start using headphones with an impedance lower than 20 Ohms or higher than 150 Ohms you will realise that you will need a dedicated headamp (might be a combo DAC/headamp like ASUS STX or Phoebus series). Of course, when driving hard-to-drive planars thing are getting more obvious.
 

IVX

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My slightly modified U7 MKII shows a very low distortions figure. The only problem is common mode noise even with AP analyzer, that should be fixable with a battery-powered laptop. In fact, 2nd and 3rd harmonics of AP generator <-130db, and modified U7 MKII shows near to -130db as well.
2020-03-29_12-59-39.png
2020-03-29_12-51-43.png
 
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trl

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My U7 Mk1 is the worst DAC I ever had: 2nd harmonic is at around -80dB and the 3rd one is pretty close, and that's for 1V RMS. However, as ADC is quite good when you need to troubleshoot an audio device or soundcard.

@IVX, what exact mod, please? Quartz swap perhaps? Thanks!
 

IVX

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I've changed the ADC for cs5381(pin2pin), added the -6V rail(AC taken from SW node of buck converter, and rectified without regulation just 4700uF), and increased +5V to +6V as well. The frontend like this(there is some mistake, the feedback resistors of X17(not shown);X18(R3) were tied to AD+ and ADC-):
2018-10-13_10-07-07.png

Oh, I forgot to mention that I have deleted all muting J-fets what I found inside of U7 MKII because they affected THD. Now U7 MKII ADC has SNR -119.4db(A) if shorted inputs.
 
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Robbo99999

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I'm using a Xonar U7 (not MkII) right now. I'm using it in USB Audio Class 2 mode using the standard Microsoft USB driver on Windows 10, completely bypassing all the Asus driver crap. Works like a charm. I'm using it in 5.1 mode and all sample rates and bit depths are available.
What do you think to U7 Mki vs expensive DACs with better measurments in terms of perceivable sound quality? From the measurements of the Mkii using only Microsoft drivers it looks like it performs fine for SNR and I guess bit depth (using Microsoft drivers)....I also think the Mki & Mkii are the same hardware last time I checked, so I guess they measure the same using Microsoft drivers.

I'm interested in this because I just realised I had an old Mki lying around in my cupboard, and I just pulled it out to use for my JBL 308p Mkii speaker system, because my SoundblasterX G6 is buggy as hell using my laptop, so figured I'd give the Xonar U7 a go. Thing is I've already ordered a Topping E30 DAC before I realised I had my Xonar U7 in the cupboard still (I also thought it would be rubbish though based on testing I did years ago when I didn't know anything 'audio' when hooking it up to a stereo system by the crappy headphone amp!). (Of course I have it hooked up via RCA right now). I'm wondering if my purchase of the Topping E30 DAC is effectively rendered useless given my realisation I have this Xonar U7!

And as a quick aside, do these types of manual switches introduce any noise or other issues, I ordered one to avoid having to switch cables all the time? https://smile.amazon.co.uk/HQ-Sourc...ual+2-Port+Audio+Switch&qid=1589625170&sr=8-1
 
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Robbo99999

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I'll be surprised if you could tell any difference between the U7 and the E30

The switch won't make any difference to sound quality. Just keep the cables as short as you can.
Thanks for the input, yeah it's good if those manual switches don't degrade the sound because they're a simple & versatile bit of kit that solves a problem pretty effortlessly (the plan!).

Yes, when I read the review for the U7 when using the Microsoft drivers it seemed to me that the U7 would be transparent and audibly as good as any other good or excellent DAC, but I wanted to get opinions of people. The one caveat is that the U7 only outputs a hair over 1V, so I'm not getting full volume on my JBL's, but to be honest those 308's have plenty of amplification power and my TV is connected to them through a miniDSP that only outputs a max of 0.9V, so by having a DAC that operates at 100% windows volume outputting a similar voltage also means less need to twiddle the volume knobs on the back of the speakers when switching between the two inputs, whilst also preserving the dynamic range of the music by having 100% windows volume (although that might be a moot point when operating at 24bit mode in windows). When my E30 DAC arrives I bet I'll find I'll have to run the speakers at only 2 on the volume dial (on back of speakers) rather than the 4 that I generally use now, that's if I run the E30 at 100% windows volume. I think my speakers don't function quite the same at only 2 on the volume dial, there's a major drop in volume going from 2.5 down to 2 so I'm also wondering if the E30 DAC could mean I'll be running the speaker amps below their ideal position, hmm.
 

Robbo99999

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How do you mean re preamp? My miniDSP from the TV has to output a max of 0.9V, won't output anymore than that. Xonar U7 outputs 1.1V. JBL active speakers accept at least 2V. You mean put a preamp after the miniDSP and Xonar U7 to boost it up to 2V? I suppose there'd be no point to that because I can just turn the volume up on back of my JBL speakers instead. How do you mean?
 

audio_tony

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You mean put a preamp after the miniDSP and Xonar U7 to boost it up to 2V

Yes, this ^^^^

Then you control both left and right channels from one place - and - you simply leave the controls on the back of the speakers set in one position.

A preamp will have input selection too, so you can select the different devices on the preamp instead of needing a switch box.
 

Robbo99999

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Ah, I see what some of the benefits might be, no need for switch box as you say and you can control final volume of everything via the pre-amp whilst keeping all the Line-Ins at their maximum line level, and no twiddling of volume knobs on the back of the speakers either. Have I got that right? I suppose one drawback to that is that you're introducing another amplifier into the chain which can increase noise levels/distortion? And then there's the cost of the preamp?

EDIT: my current setup doesn't really need a preamp there considering the Xonar U7 and the mini DSP both output roughly the same voltage (1.1V & 0.9V), so volume twiddling on the back of the speakers shouldn't really be necessary when I have the U7 & miniDSP hooked up to the two inputs of the switch box I've ordered. The difference will occur when my E30 DAC arrives where it can output 2V...I may just use that for optical connection to the TV and it would output 2V to the miniDSP (max it can accept), and I'd use the volume control on the E30 to control TV volume. (At the moment I control TV volume via TV remote as I'm currently using the analog Line Out from the TV to miniDSP.). It might be sacrilege to use the E30 as TV/movie rather than music from my laptop (which is Xonar U7 currently), so I will also trial E30 DAC connected to my laptop to see if any upgrade in perceivable sound quality vs the Xonar U7 (I could volume match using UMIK microphone)...if it's not a clear difference then I'll use the E30 for the TV like I explained already, because maybe the weakest link currently is the DAC and Analog Line Out built into my TV (Sony KDL-42W653A).
 
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audio_tony

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Have I got that right?

Yes.

A preamp need not be expensive, and shouldn't add any noise (it's really not difficult to make a quiet preamp).

If you're handy with a soldering iron, you could even build your own.

There is a Tensai preamp on Ebay at the moment for £99 - it's vintage but good.

You could even use a so called 'passive preamp' if you can keep your cables short enough (in particular cables from preamp to speakers).

Links:

Passive preamp

Tensai Preamp
 
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Robbo99999

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Ah, I found it...it says it has an SNR of 75-90dB depending on connection I guess (didn't understand the terminology) - that sounds like sound quality degradation to me. I think the whole preamp thing is unnecessarily expensive & complicated for me at the moment whilst also looking like it will degrade sound quality, even if it could simplify usage of all the products in day to day use - one master volume remote. I'll see where I'm at with the manual switch and my E30 vs Xonar U7 listening tests once the E30 arrives.
 

Robbo99999

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My slightly modified U7 MKII shows a very low distortions figure. The only problem is common mode noise even with AP analyzer, that should be fixable with a battery-powered laptop. In fact, 2nd and 3rd harmonics of AP generator <-130db, and modified U7 MKII shows near to -130db as well.
View attachment 56121View attachment 56122
A quick question about what you're showing here. Is one of the things you're showing that the Line Out DAC performs better in terms of SINAD with 1Vrms rather than 1.121Vrms, so this DAC provides best sound quality at 88% Windows Volume for music playback? Or are you showing the Line In ADC performing better at 1Vrms rather than 1.121Vrms? I'm just to make sure what the best Windows Volume / Volts would be for music playback from the Line Out in terms of SINAD/sound quality.
 
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Tasslehoff

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It worked perfectly fine with ASIO4ALL in Windows 8.1 for me, first time, no fiddling about. However, I haven't tried it in 24 bit.
I think PCs are generally an unreliable platform for testing USB powered DACs.
Audio performance varies from one PC to another because the quality of the PSU generally varies also. The power source is crucial for audio performance.
Electromagnetic interference varies too.
As does memory latency and background CPU activity, and probably USB audio latency.
Laptops generally do not have great latency but at least they have the choice of using it's battery as a clean power source.
Perhaps it's worth measuring how USB audio performance varies?
 
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