[GodsInHisHeaven]

What is the usb chip of the specific unit ?
Has any other usb dac worked well with your pc ?
Have you tried different usb cables and all USB ports of your pc ?
Have you tried to feed it spdif ?

 
- Amanero combo 384
- FiiO Kunlun E18 worked just fine (my Mainboard -> MSI Z97)
- Yes and yes
- No, it has to work with USB.
 
I have a modded Asus STX 2, so I used the RCA of my sound card and the NFB28 as pure amp. Same thing here, H and L to low in volume and F/5 distort ...
 
Is the AMP defect?

 

[i019791]

You could try another headamp fed from your Asus before declaring the amp section defective.
I would try spdif in any case, and trouble shoot sending an email to Audio Gd.
By the way, the usage of the button at the back is described in the user manual at Audio Gd site.

 

[mtoc]

Lord, looks like nfb28 has no coax input?

 

[elwappo99]

 

What is the usb chip of the specific unit ?
Has any other usb dac worked well with your pc ?
Have you tried different usb cables and all USB ports of your pc ?
Have you tried to feed it spdif ?

 
- Amanero combo 384
- FiiO Kunlun E18 worked just fine (my Mainboard -> MSI Z97)
- Yes and yes
- No, it has to work with USB.
 
I have a modded Asus STX 2, so I used the RCA of my sound card and the NFB28 as pure amp. Same thing here, H and L to low in volume and F/5 distort ...
 
Is the AMP defect?

 
Is the windows system volume turned down?
 

Lord, looks like nfb28 has no coax input?

 
I see a coax and BNC on the back?

 

[GodsInHisHeaven]

   
Is the windows system volume turned down?
 
 
I see a coax and BNC on the back?

 
Thanks for the support guys.
 
I think the USB/DAC is okay. The AMP itself seems to have a problem.
 
Only at a certain volume (around 45 db)  the distortion starts, no matter the windows volume, programm volume and NFB-28 volume setting.
 
When I use a very soft EQ for more bass at the border before the distortion starts the bass is all distorted. 
 
The not distorted SQ at a low volume was very nice though.

 

[PinkyPowers]

Thanks for the support guys.

I think the USB/DAC is okay. The AMP itself seems to have a problem.

Only at a certain volume (around 45 db)  the distortion starts, no matter the windows volume, programm volume and NFB-28 volume setting.

When I use a very soft EQ for more bass at the border before the distortion starts the bass is all distorted. 

The not distorted SQ at a low volume was very nice though.

Contact Audio-GD immediately. This is not right.

Kingwa is very responsive and helpful
audio-gd@vip.163.com

 

[elwappo99]

 

   
Is the windows system volume turned down?
 
 
I see a coax and BNC on the back?

 
Thanks for the support guys.
 
I think the USB/DAC is okay. The AMP itself seems to have a problem.
 
Only at a certain volume (around 45 db)  the distortion starts, no matter the windows volume, programm volume and NFB-28 volume setting.
 
When I use a very soft EQ for more bass at the border before the distortion starts the bass is all distorted. 
 
The not distorted SQ at a low volume was very nice though.

 
Huh, total bummer. 
 
Pretty rare since Audio-gd usually tests their units for 200 hours before they send them.

 

[mtoc]

can't see coax here http://www.audio-gd.com/Pro/Headphoneamp/NFB282016/NFB282015H1.JPG

 

[john57]

can't see coax here http://www.audio-gd.com/Pro/Headphoneamp/NFB282016/NFB282015H1.JPG

There is one IN4 right next to IN3

 

[PinkyPowers]

can't see coax here http://www.audio-gd.com/Pro/Headphoneamp/NFB282016/NFB282015H1.JPG

The website does say it has Coaxial, and Input 4 looks like it might be it.

I couldn't find any resource that listed which was which. But based on that photo you posted, I can surmise this:

Input 1 = USB
Input 2 = Network Cable
Input 3 = Optical
Input 4 = ? Doesn't have L&R channels, so must be digital. RCA design. That leaves Coaxial, yes?
Input 5 = L&R RCA Analogue
Input 6 = L&R XLR Analogue

 

[john57]

IN2 is the I2S connection using a RJ45 jack

 

[PinkyPowers]

IN2 is theI2S connection using a RJ45 jack

I don't know what any of that means.

 

[mtoc]

Has anyone had the opportunity to compare the NFB-28 with and without TCXO upgrade side by side?

I have the NFB-28 without TCXO (Not my intention. I would have ordered it but I was not aware of such an option when I purchased it). After spending a month listen to my LCD-XC with it and I am come to the conclusion that the DAC in the NFB-28 is lackluster. It doesn't to headphones as great as the LCD-XC justice and there is a lot more potential untouched in them.

I am wondering if the TCXO is what is missing to bring out the best in the DAC. However, I have a feeling based on how much feels like it is missing from the NFB-28 DAC that it is simply not because of the TCXO.

I guess small DACs and all in one units just cannot cut it for me anymore after owning a REF1 for so long.

 
I have a question, this TCXO upgrade on the nfb28, is it a upgrade on the internal usb interface? If so, when we use our external usb interfaces, this tcxo has nothing to do with the sound. Still need some confirmation...

 

[Stillhart]

   
I have a question, this TCXO upgrade on the nfb28, is it a upgrade on the internal usb interface? If so, when we use our external usb interfaces, this tcxo has nothing to do with the sound. Still need some confirmation...

 
From the Audio-GD website:
 
2, Upgrade TCXO for USB-32 and ES9018 for slight improve on the sound transparency .
     There two TCXOs can be upgrade  for the USB-32 and ES9018, cost is USD20/per,  without shipping delay .
 
One TXCO is for the USB and one is for the DAC chip so one acts as you describe and the other does not.

 

[wuhanclan]

Can I switch between variable and fixed dac output from the buttons on the front without swapping a jumper?