Wisdom in mind,   enthusiasm at heart.

NFB-28 (ES9028Pro )

Discrete  DAC+ Headphone amplifier / Preamplifier
With XLR / RCA analog inputs
DSD , DXD support from USB & I2S Input
32bit / 768K Sabre ES9028Pro
32bit / 384K Asynchronous Transfer XMOS U208 Chip

Please note:
         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 unit  had design the analog idle input short circuit (In 5 and In 6) for avoid the disturb between different sources.
         This design also applied in a lot high end brand devices.
         The working theory :  Without the idle input short circuit ,if the input 5 and input 6 had connect two extra DACs,  while users select the either input 5 and input 6 , the another input signal will fire through the circuits and mix  into the using signal, even though this signal is  weak  but still can degrade on the sound quality.
          With the idle input short circuit function : if user select either the input 5 and input 6, the another input signal 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 unit analog input, but connect with other amps simultaneity.
      2, The same extra source connect to the unit input 6 and input 5  at simultaneity.
          

I2S-RJ45 input format:
( 3.3V level ,  we can't guarantee the I2S input can cooperate with all I2S output devices.
( The I2S transmit want to take care the transmit cable  )
Pin 1 : SDATA
Pin 3 : LRCK
Pin 5 : SCLK
Pin 7 : MCLK
Pin 2,4,6,8 GND
 Customer can custom order the different define of the I2S  pins free .
Please note: Don't hot push / pull of the I2S cable. Any time must power off the units then push or pull the I2S cable.

Gain button:
Select the Fast / Slow volume control characteristics.
        H: Fast.  64 steps range.  
        L: Slow. 100 steps range.
        F: (Full ) High gain mode. 100 steps range. (For the low sensitivity headphone like the HE-6 or the source had low output voltage level)
        S: (Super)High gain mode. 64 steps range. (For the low sensitivity headphone like the HE-6 or the source had low output voltage level)

The button on rear : Pull out for the DAC / preamp without volume control , Push into for the DAC / Preamp with volume control. The headphone output always had the volume control. Please operate the button while the unit power off .

The display auto dark :  Push into the jumper is auto dark .Please operate the jumper while the unit power off .


DSD / PCM support from I2S input :
The DSD/PCM support not only from the USB input, but the I2S input.   The NFB-28 can detect the I2S input signal, if input DSD signal, it will auto to remove the DSD pop noise while select the DSD track .