Review and Measurements of Audio-gd NFB-27.38 DAC and Headphone Amplifier

[Jimster480]

Why? They say it is UAC2 compliant which means it should be plug-and-play with Windows 10. If it is not, they need to look into why that is the case. Installing drivers is not the answer.

Also, the drivers are sent from a third-party, using .rar format. There is no app to open such a format on Windows 10 by default. So you have to go and find yet another program to install (many of which come with crapware) just to open the darn package. They need to provide this in .zip format as a minimum, and own the package on their own website.

Ultimately I did not ding them on this other than noting the problem. I am accepting on faith that others can make it work.

Winrar is free from Rarlabs and its the developing body behind the rar format.

 

[Jimster480]

I've found Win10 Fall Creators Edition to be a bit fickle with USB Class 2 Audio. When I purchased my Sabaj Da3, naturally, their web site was down for 3 days and I was unable to download the drivers for it. Win10 partially recognized the XMOS XU208 that many DACs use, but not completely. So, for example, it worked in Foobar 2000, but not Kodi.

I'll give both XMOS and Sabaj credit - once the website came back I was able to download properly signed drivers for Win10 and it has worked like a champ. While trying to find alternative drivers I found out the XMOS has program to provide signed drivers for manufacturers who use their products. I don't remember the specifics, but for low volume it was a free service and for higher volumes not especially expensive.

Where is this program? I was looking for such a program but found that XMOS doesn't provide drivers directly for their products?

 

[Timbo2]

Where is this program? I was looking for such a program but found that XMOS doesn't provide drivers directly for their products?

It's available via Thesycon. Essentially OEM only and coded to the PID of the USB device. So you can't use Firm A's driver with Firm B's device even with the same XMOS chip providing the USB interface.

http://www.xmos.com/download/private/USB-Audio-2.0-Driver-for-Windows---Overview(3.34.0).pdf

 

[amirm]

Speaking of Thesycon, I just went to uninstall their older drivers from my desktop machine and it complained that the uninstall is not compatible with Windows 10! So I can't even remove the darn software/driver.

Did I say I hate having to install drivers? I thought I did.

 

[RayDunzl]

Did I say I hate having to install drivers?

Why do you have to "install" things in the first place?

*remembers early Macintosh - drag one file (which was really a bundle of resource files) to anywhere and it is "installed".

Want to delete it? Delete the "file" - drag to trash can.

*has no idea how they do it now.

 

[amirm]

Why do you have to "install" things in the first place?

Because until Creators update of Windows 10, USB audio class 2 device was not supported. So drivers had to be installed. So to run my Berkeley alpha USB to S/PDIF bridge, I had to install that package.

 

[Blumlein 88]

Because until Creators update of Windows 10, USB audio class 2 device was not supported. So drivers had to be installed. So to run my Berkeley alpha USB to S/PDIF bridge, I had to install that package.

And who is it that once was responsible for audio in Windows?????

 

[Wombat]

And who is it that once was responsible for audio in Windows?????

He may have been away on that morning.

 

[amirm]

And who is it that once was responsible for audio in Windows?????

 

[trl]

[...]In most cases, balanced is twice the power. Balanced mode is just 2 amps driving each channel separately.[...]

It's actually more than twice, it's up to 4 times more power in balanced operation vs. single-ended operation.
In stereo "balanced operation" there are 4 internal amplifiers, each one handling "+" & "-" for every channel vs. single-ended operation when only 2 of these amplifiers are used and the output voltage is referenced to the GND. In balanced operation outputs are not referenced to GND.

 

[trl]

[...] To keep it simple: Have ever ever measured an Valve amplifier or a phono record player? If you measure them all you will throw them all in the bin according to the reviewers opinion. This is of course bull shit. Valve amplifiers can sound really nice and so do phono record players! [...]

I've seen measurements done by Atomicbob and Solderdude for couple of Garage1217 valve amplifiers and both sine and square waves were looking absolutely awesome from 20Hz to 20kHz. So there is life after semiconductors, indeed.

 

[trl]

Just got permission to do so. There is a ton in there though so it may take a bit....

Looking forward for the teardown, Amir.

Meanwhile I can only see manufacturer pics here, so lots of components without much space between the stages, but with decent shielding anyway. Personally, I don't much like the cheap heatsinks and the transformers, but apart of that if such device was measuring well when manufacturer did the AP tests, then perhaps it was well designed after all, but maybe the PCB got changed or got lowered in the quality...who knows. I've measured in the past 1.2 ohms between 2 ground points being 2 inches apart, but being on different sides, so sh..t could happen without manufacturer's will and notice.

 

[sssn]

To me, it looks more like Audio-GD is more concerned about how their PCBs look instead of how they perform. Proper PCB design has nothing to do with neat rows and columns etc.

 

[Frank Dernie]

I've seen measurements done by Atomicbob and Solderdude for couple of Garage1217 valve amplifiers and both sine and square waves were looking absolutely awesome from 20Hz to 20kHz. So there is life after semiconductors, indeed.

I got all excited about awsome 20Hz square wave from a valve amp until I checked which one only to find they aren't amps at all but preamps with a headphone outlet

I would love to think somebody had come up with an output transformer at last which worked well over the whole frequency band (with enough power to be worth using into a real speaker) but clearly not.
Valve preamps have never been much of a problem, IME.

 

[Krunok]

Listening Tests
Since I could not get the USB interface working without drivers on Audio-gd NFB-27.38, I used a Topping D10 DAC as the USB to S/PDIF bridge. I then ganged up both the Topping DX7s and Topping D10/Audio-gd combo in Roon so that I could play my reference tracks in sync. Levels were matched using a 1 Khz tone well below max level of Topping DX7s (and hence much, much lower than max level of Audio-gd NFB-27.38). I then used an AB switcher to instantly switch between on device versus another.

Testing was performed using Sennheiser HD-650 and HifiMan HE400i.

I could detect no difference in bass or mid-frequencies. In high-frequencies though, there was a subtle difference. They were a bit more emphasized in Audio-gd which gave a slightly more airy and open sound to Audio-gd. But as I focused on them, I realized the high notes are being distorted with the highs having a "sizzle" to them. That exaggerated their presence which could be to some people's liking. For me, as I focused on the same in Topping DX7s, I realized they were very clean and well defined whereas they were "blown" on the Audio-gd NFB-27.38 leading me to prefer the Topping version better.

I should emphasize that the above is very subtle effect. If I did not focus on it, I would find the two DACs to sound the same. Then again, younger people with better high frequency hearing than me will detect the above effect better than me which may lead them to more preference or dislike as the case may be. If you are older than 50, you can safely go with my impressions.

These words, at least in my eyes, are perfectly explaining the truth behind subjective listening tests vs objective measurements: not only that the difference, that is so obviously shown on measurement equipment, can easily be overlooked during listening tests, but can also be found to be more appealing to some people.

 

[Krunok]

什葉派

LOOOL

 

[SIY]

I would love to think somebody had come up with an output transformer at last which worked well over the whole frequency band (with enough power to be worth using into a real speaker) but clearly not.

I think some of Menno's toroids will do pretty well in that respect. And of course, Berning's "virtual" transformers work as well as claimed. See figure 2 here, for example:
https://www.stereophile.com/content/linear-tube-audio-zotl40-mkii-power-amplifier-measurements

I'll show some similar data in my upcoming review of the Linear Tube Audio Ultralinear.

 

[Krunok]

Paraphrased: "More distortion is better if it sounds more musical."

LOOL - and that is exactly while I'm keeping my Audio Aero tube class A amp! I'm of course aware that its 0.2% THD and 70dB SNR will never sound as accurate as even a half-decent class D amp but looking at him nicely glowing in the dark I cannot help reminding myself how "musical" it is!

 

[Krunok]

It can be when it comes from random sources overseas. Drivers can also cause significant instability as compared to being class compliant and using OS manufacturer's driver.

What do we do if the next OS version comes out with slightly different driver interface and their drivers no longer work?

What value do we get from having to install drivers? None that I can see.

There is a reason Microsoft warns you when you try to install unsigned drivers. It is not something good that you want to do unless you really need to do so.

While I agree with your statement that if they say device is UAC2 compliant it should work with generic driver I also believe it is usually better to use manufacturer provided driver rather than generic Windows driver.

In my experience that is also the truth with UAC2 driver as, although it was written by Thesycon, it is still not as good as manufacturer provided customized driver also developed by Thesycon. For example, I have noticed generic UAC2 driver has a tendency to produce drop outs on the same machines where customized driver works without any issues.

What I find strange is that Audio-gd isn't providing driver in a professional manner, while Topping is, which I can't really justify, especially considering the difference in price.

Btw, this whole USB thing is anyhow outdated in my opinion. My notebook is not really that close to my audio equipment, so what should I do? Run a long USB cable over my living room hoping that my wife won't throw me and the cable out the moment she sees it? Buy some USB server hoping that its asynchronous transfer mode will work good enough for the bit perfect transfer of HiRes audio? Or maybe invest few bucks in Raspberry Pi, connect it to my network, attach DAC to its USB port and try to make UPnP renderer out of it? I decided to go for the latter, so in a few days I will know if it works..

 

[Krunok]

Speaking of Thesycon, I just went to uninstall their older drivers from my desktop machine and it complained that the uninstall is not compatible with Windows 10! So I can't even remove the darn software/driver.

Did I say I hate having to install drivers? I thought I did.

I have learned my lesson with cases like that so now I create restore point before installing a driver and than restore to it when I don't need it any more. Quick and simple, especially in the situations like yours where you need to test many devices on the same machine. Anyway, I'm sure you know how it works..