Please not:
          The R-28 had built in fully dedicated discrete R-2R resistor ladders DA modules. Based on some users feedback from Audio-gd other's R-2R products, it need longer burn in time to achieve the best sound quality and performance.
          Even it had burn in over 100 hours before shipping , but we are advice customers burn in it more than another 500 hours.
          You can power on it with playing music but shut down the volume for quickly finished burn in if you are at home.
          The mini remote shipped without battery because the either DHL and EMS limit shipping by plane , customers want to buy one CR2025 battery and assemble in the remote.



Input mode: 
Push the button "Input" for select the input sources .
Input 1: HDMI-IIS input.
Input 2: USB input.
Input 3: Optical input.
Input 4: RCA - coaxial input.
Input 5: XLR analog input.

Gain mode: 
Push the button "Gain", the display will show between " L, H" .

"L" mean the unit working on low gain (100 steps and 12DB).

"H" mean the unit working on high gain (100 steps and 22DB).
We have applied the new gain technology ,no any switches,relays or parameter of the amp change while change the gain modes so the sound quality is exact same in different gain modes. Users just want to choice the better mode for easy adjust the volume level.



Output mode: 
Push the button "OUT", the display will show between " P , H".

"P" mean the unit output from XLR / RCA / ACSS from rear. XLR and RCA can connect to two amps in same time.

"H" mean the unit output for headphones on front plate.

The DAC/PREAMP output mode selector : 
Pull out , XLR / RCA /ACSS output as decent DAC, in this mode, the display show "d" instead "P" and the volume number show "--" ,the volume can not adjust anymore (The headphone output mode has not effect).
Push into , XLR / RCA /ACSS output as preamp .
Headphone output mode has not any effect by this selector .


 

Setting menu display :


　

How to active the digital setting mode:
         The "OUT" and "Input" buttons has dual functions.
         While the input between input 5 , the "OUT" button can select the output mode between "H" (Headphone output) and "P" (Preamp output) .
         While the input is between 1 to 4, the "OUT" button become dual functions.
         In case, push the "OUT" button one time, the left first display flashing around 3 seconds, in term if the "OUT" button has not push again, the output mode change either "H" or "P".
         If the "OUT" button push again while the left first display flashing, the unit go into the digital setting mode.

OUT button :
          While the unit had went into the digital setting mode, the one digit display will blink for active the function setting , push the "Input" button can change function .
         While the display blink, push "OUT" again , the right next one digit display will blink for setting .

"Input" button:
           While the display non blink, for select the input sources.
          While the display blink, for setting the digital process functions.

Left 1st display : Oversampling 
         "O" for select oversampling, "N" for select NOS mode.

Left 2nd display : OS and NOS modes
          While OS setting on "O" mean the DAC working under oversampling mode, lower number OS modes sound became warmer and smoother. Or depend on your sense .
         Mode "0" : class technology NOS mode.
         Mode "2" : 2X oversampling.
         Mode "4" : 4X oversampling .
         Mode "8" : 8X oversampling.

         While OS setting on "N" mean the DAC working under NOS mode, it has one mode now, it is the full new NOS configure design.

Left 3rd display : (Simulate vinyl record  sound flavor) :
           Active (1) : Simulate vinyl record sound flavor . While active this function, I are advice setting to OS0 or NOS mode. But in fact, this function can working with any setting mode.
　

Left 4th. display :  ( Preamp and DAC output mode setting)
          Set to P, the output mode can switch between H (headphone) and P ( preamp) .
         Set to d, the output mode can switch between H (headphone ) and d (DAC).

Left 5th. display : Display
         Active (1)  the display auto dark, the display will become dark in around 10 seconds after stop operate any buttons . Disable (0) the display auto dark, the display  light always.

　

Setting examples:(Must select the input channel between 1 to 4 )

1. Settings for most neutral sound (8x oversampling, not simulating the TDA mode):
         Push the "OUT" button 1 times, when the 1st digit blinking, push the "OUT" button 1 times for into the setting menu .
         When the 1st digit blinking, push the "Input" button set it to "O" .
         Then push the "OUT" button one more time, the 2nd digit will blink, then push the  "Input" button to set the value to "8".
        Then push the "OUT" button one more time, the 3rd digit will blink, then push the  "Input" button to set the value to "n".
        Waiting 6 seconds the setting menu quit and save the setting.

2. Settings for OS0 and vinyl record  simulation mode:
        Push the "OUT" button 1 times, when the 1st digit blinking, push the "OUT" button 1 times for into the setting menu .
         When the 1st digit blinking, push the "Input" button set it to "O" .
         Then push the "OUT" button one more time, the 2nd digit will blink, then push the  "Input" button to set the value to "0".
        Then push the "OUT" button one more time, the 3rd digit will blink, then push the  "Input" button to set the value to "S".
        Waiting 6 seconds the setting menu quit and save the setting.
        

3. Settings for NOS mode with vinyl record  simulation (new option combination to get the warmest and smoothest sound ):
        Push the "OUT" button 1 times, when the 1st digit blinking, push the "OUT" button 1 times for into the setting menu .
         When the 1st digit blinking, push the "Input" button set it to "n" .
        Then push the "OUT" button 2 more times, the 3rd digit will blink, then push the  "Input" button to set the value to "S".
        Waiting 6 seconds the setting menu quit and save the setting.

4. Settings for DAC output mode available:
        Push the "OUT" button 1 times, when the 1st digit blinking, push the "OUT" button 1 times for into the setting menu .
        Then push the "OUT" button 3 more times, the 4th digit will blink, then push the  "Input" button to set the value to "d".
        Waiting 6 seconds the setting menu quit and save the setting.

5. Settings for DAC auto dim:
        Push the "OUT" button 1 times, when the 1st digit blinking, push the "OUT" button 1 times for into the setting menu .
        Then push the "OUT" button 4 more times, the 5th digit will blink, then push the  "Input" button to set the value to "A".
        Waiting 6 seconds the setting menu quit and save the setting.
        10 seconds later the user stop operate the buttons and knob, the DAC display shut auto, only leave a "-" for show the power is on.

       
HDMI definitions : (Apply HDMI transmit the IIS signal, the pin's definitions must exact same , and not promise compatible with other brands)

This product don't need the source MCLK signal but even the source has MLCK output but has not effect .


Firmware update now features:

         

10-pin UPDATE PORT:
         To connect the Altera Blaster and proceed with an FPGA firmware update from Windows, using the Altera programming software. These updates are meant for upgrading the functionality and/or sound quality .
FPGA firmware download and update guide:
        http://www.audio-gd.com/Firmwaredownload.htm
UPDATE PORT switch :
        For updating the built-in Amanero module's firmware through the USB input.
Please note:
        Don't touch this switch when the product is powered on unless proceeding with an Amanero firmware update, underwise you will be forced to proceed with an actual update, as the firmware will have been erased.
Amanero firmware download and update guide:   
        https://www.amanero.com/combo384_firmware.htm
Amanero firmware update guide :
         http://www.audio-gd.com/Pro/dac/Amanero/AmaneroEN.htm
         Please download the update tool and guide from Amanero's official web .
         In the official update guide, there is a step requiring that two pads be shorted more than 1 second on the Amanero module , while with this product, the end-users only need to push the black button for more than 1 second in order to perform the same step.
         The other update steps are the exact same as in the official guide.

Please note:
Some few customer feedback they accidentally touch the Amanero update button cause the firmware delete, Since 23rd. July 2021 , the product ship without connect the update button wire, if customer want to active the update button feature, connect by self.