Built In 4 Groups of  DA-8 R-2R Modules
Built In FPGA Processor to Reject Jitter 
DSD , DXD 32bit / 384K Support From USB / HDMI
Built in real balanced headphone amp.
Built with OCC and Hi-end parts

Custom order options:

Option 1:Custom order replace the ACSS output by RCA outputs free.

Option 2:Upgrade two stock clocks to Femtosecond  TCXOs for slightly improved the sound transparency ,price is USD40 .

Option 3:Upgrade two stock clocks to Accusilicon ultra clocks, price USD76. If customer choice option 3, the option 2 don't need choice.
         
Option 4:Upgrade the 2 pc Crystek Femtosecond clocks on Amanero USB interface, price USD15.


Option 5: Custom order High Gain model for the HE6 and low sensitivity headphones:
      The R-28 default had 16DB gain, customers can custom order extra +6 DB gain, in total 22DB gain,  had better match with the headphone which is sensitivity low than 95DB.
       Price is USD20.

Option 6: Custom order Isolator for Amanero USB input for separate the GND between computer and DAC,price is USD30, sound transparency improve a little.(The unit after upgraded USB isolator, it can not support cell phone USB connect .)