[rudibe]

It's probably picking up noise from the computer via USB. Try disconnecting the USB cable, in case the hiss goes away, you might want to try setting up a optical connection from the PC to the DAC (if possible).

 

[Jokanok]

It is not the USB connection. I have the same issue while connected via optical to my Airport Express.
 
I have extensively checked the possibility of electronical noise coming from the USB connection of my laptop.
 
I have recorded a "silent" audio file with the help of Audacity. I played this file from my laptop using its power supply as well as only its battery, and while streaming music over wifi, playing some 1080p movies from my SSD and  streaming youtube over internet (all at the same time!). No abnormal sounds whatsoever.
 
I also compared the optical and usb input of the NFB-11 and find the sound reproduction with USB better. I used JRiver with Asio settings for bitperfect reproduction via USB, and iTunes set to max volume also for bitperfect reproduction to my Airport Express via optical. The difference in SQ could be due to the NFB-11's electrical design, but also to the Airport Express' design, or the difference between iTunes and JRiver could possibly be the explanation. Honestly I have no clue.  
 
The noise is only audible at rather high volume. Could it be a noise because of a grounding issue between my DAC and AMP connected via RCA? I have no other amplifier to test this.
 
Thanks a lot for replying!

 

[cel4145]

The pre-amp outs on my NFB-11 work fine for me with my TA2021 t-amp.

The pre-amp outs on the NFB-11 have a higher gain than the line out, from what I understand. Try turning your amp all the way down, connect it, and using the line out on the SMSL and its volume control and see if that causes a problem.

 

[cel4145]

The noise is only audible at rather high volume. Could it be a noise because of a grounding issue between my DAC and AMP connected via RCA? I have no other amplifier to test this.

Yes. It's possible there is a ground loop problem. Do you have your computer, NFB-11, and SMSL amp running off the same jack off the wall (via a power strip)?

 

[Jokanok]

The pre-amp outs on my NFB-11 work fine for me with my TA2021 t-amp.

The pre-amp outs on the NFB-11 have a higher gain than the line out, from what I understand. Try turning your amp all the way down, connect it, and using the line out on the SMSL and its volume control and see if that causes a problem.

With line-out, do you mean the headphone output of the NFB-11? I am waiting for the delivery of an order for a 6,3mm to 3,5mm jack adapter in order to test this.

 

[Jokanok]

Yes. It's possible there is a ground loop problem. Do you have your computer, NFB-11, and SMSL amp running off the same jack off the wall (via a power strip)?

Yes they are all connected to the same power strip. I will test it with another wall-plug and come back on this.

 

[rudibe]

  However, with my amp connected to the NFB-11 and my amp also set at max volume, while I increase the volume knob of the NFB-11 (being used as a pre-amp), a  proportional increasing noise comes out of the speakers.

Try decreasing the volume on your amplifier and increasing the gain on the NFB (low/high gain also affects the pre-amp output, at least on the variable setting). Otherwise, use the fixed level output mode and alter the volume on the SMSL.
 
SMSL's power supply might also be affecting other electronics, at least mine el-cheapo switching power supply does (SMSL 24V / 2.5A) - when it's plugged into the power strip, my Hypex amp starts buzzing.

 

[Jokanok]

 
Yes they are all connected to the same power strip. I will test it with another wall-plug and come back on this.

 
The power supply of the SMSL has no earth connection on its AC inlet. I have switched momentarily to another wall plug but this did not make any difference.
 
I must say that the noise is well below the "noise floor" and therefore as such not audible at playback.
 
As most D-amps are dead silent, I thought that this slight noise is maybe due to the design of the A-type preamplifier within the NFB-11. Or should it also be dead silent at maximum volume? And if so, I have probably a ground issue. But the amp only takes DC. Do you think this issue may be remedied if I would use a properly grounded AC-DC converter/power supply? 

 

[cel4145]

With line-out, do you mean the headphone output of the NFB-11? I am waiting for the delivery of an order for a 6,3mm to 3,5mm jack adapter in order to test this.

The RCA jacks on the back can be used in pre-amp mode or line out mode via the switch on the front of the NFB-11. Try line out mode.

 

[Jokanok]

  Try decreasing the volume on your amplifier and increasing the gain on the NFB (low/high gain also affects the pre-amp output, at least on the variable setting). Otherwise, use the fixed level output mode and alter the volume on the SMSL.
 
SMSL's power supply might also be affecting other electronics, at least mine el-cheapo switching power supply does (SMSL 24V / 2.5A) - when it's plugged into the power strip, my Hypex amp starts buzzing.

 
I tried all the different volume settings on the NFB-11. Made no difference!
 
I also am of the opinion that the cheap SMSL power supply is probably the culprit. I have ordered a SMPS300RS board (Connexelectronics) as a replacement. Once I have built a good quality power supply with proper grounding and have tested it, I will certainly come back on this issue.
 
Thanks a lot for your interest.  

 

[Boogirl]

Question- I have an audeze lcd 2.2 paired with a violectric v200. I originally bought the NFB 11.32 to use the device as my amp and dac then bought the violectric to use the NFB 11.32 as the dac connected to the violectric. Is this a dumb idea, anyone use their NFB 11.32 purely as a dac? Thanks in advance.

Not a dumb idea. I'm thinking of doing something similar, but instead either with a Schitt Lyr 2 or mayby a Burson Soloist SL. I want to go for the Lyr 2 due to it being a tube and also cheaper than the Burson but I cam concerned as to whether this would be a big jump from the NFB 11's amp. When ever I try and look for information regarding using the NFB 11 DAC feeding another headphone amp I can't seem to find any info as to whether an improvement will be had.
 
Has anyone on this forum used the NFB 11 (or even the NFB 15 for that matter) as purely a dac and fed another superior headhphone amp? If so, please specify which headphone amp and also anyy advise on Burson or Lyr coupled with NFB would be really appreciated.

 

[return78]

The RCA jacks on the back can be used in pre-amp mode or line out mode via the switch on the front of the NFB-11. Try line out mode.

Using Ouput button?
 
HP = HP
Variable = ?
Fixed = ?

 

[cel4145]

Using Ouput button?

Yes

 

[Sam21]

variable means you can use the volume knob on the nfb-11...the output varies when you turn the knob up or down.
 
fixed means the volume knob is disabled and only a fixed volume is outputted.

 

[return78]

Which is pre-amp mode? Variable or fixed?