Wisdom in mind,   enthusiasm at heart.

NFB-28 (Version 2014 )(DSD / DXD )(Since 1st May 2014)
Discrete  DAC+ Headphone amplifier / Preamplifier
With XLR / RCA analog inputs
DSD , DXD support from USB
32bit / 384K Sabre ES9018
32bit / 384K Asynchronous Transfer  USB-32 Chip

Please note:
Power On :
          Source power ON ---->    The product power ON ----> Amp power ON
Power Off:
          Amp power OFF ---->  The product power OFF   ---> Source power OFF .

         In USB model, start the computer then power on our product is necessary because our products have not applied the USB+5V for less interrupt from the computer.
        

Discontinued the analog idle input short circuit function:
         The NFB-28  had design the analog idle input short circuit for avoid the disturb between different sources.
         This design also applied in a lot high end brand devices.
         The working theory :  The input 6 and input 5 had connect two extra DACs, without the idle input short circuit function, while users select input 6 , the input 5 signal will fire through the circuits and mix  into the input 6 signal, even though this is very weak signal but still can degrade on the sound quality.
          With the idle input short circuit function : if user select input 6, the input 5 will short circuit then no any signal fire through circuits , can keep the sound quality had not degrade.
       Below case users want to discontinued the idle input short circuit function, pull off the 4 jumpers as mark on the photo:
      1, The same extra source not only connect the NFB28 analog input, but connect with other amps simultaneity.
      2, The same extra source connect to the NFB28 input 6 and input 5  at simultaneity.
          

How to set the NFB-28 DAC output level?
         Turn the NFB-28 volume to 50 steps, its DAC output level will same as the standard DAC.

Setting the NFB-28 have extra 6DB gain for analog inputs:
            The 4 pcs jumper are pushed into the socket labeled in the red pane  for boost the analog input have extra +6DB gain for the  low output level devices. (Please pull out the power cord before the cover of the chassis is taken off .)

               

Setting the NFB-28 have warmer sound:
            The 4 pcs jumper are pushed into the socket labeled in the red pane  for setting the NFB-28 have warmer sound. (Please pull out the power cord before the cover of the chassis is taken off .)
             

DAC/HP button:
Select the output modes.
         H:   Headphone output.
         P:   Preamplifier output. 
　

Gain button:
Select the high / low gain mode.
        H: High gain mode at +12dB.    
        L: Low gain mode at 0dB.
　

Selector button:
Select the input sources.   
        1: USB input.
        2: Optical input.
        3 : Coaxial RCA input.
        4 : Coaxial BNC input.
        5 : Analog RCA input.
        6 : Analog XLR input.

Volume knob:
        Turn Left :     Reduce the volume.
        Turn Right  : Increase the volume .
        Because different sources may have different output level, so before select the input sources, reduce the volume is more safe .