Headphones DAC + amp

DAC: I2S over USB with AK4396

Buffer: Joachim Gerhard Filter Buffer for ES9022

Volume Pot: 10k

AMP: “The Wire” BAL – BAL

Casti: HD650

Take signal directly from AK4396 chip, feed “The Wire” Bal-Bal

Mods:

1. Mod AK4396 carrier board to directly feed “The Wire”
2. Adapt input of the wire for AKM load
3. Rewire HD650 for Bal-Bal
4. Figure out what type of signal attenuation to use
   1. digital volume from AKM
   2. between AKM and The wire
   3. between The wire and the headphones

Documentation:

1. “The Wire” Bal-Bal – schematics page 3
2. I2S over USB with AK4396
   1. AK4396 chip data sheet
      1. load resistance min 1kΩ AC load and 1.5 kΩ DC load page 10
   2. I/V stage schematics
   3. instructions for board modification

    

What type of signal attenuation to use

1. Digital volume from AKM
   1. Pros
      1. no attenuation in the analog section
   2. Cons
      1. XMOS firmware need to be changed for software volume control
      2. Add  an external controller for AK4396 chip eg: arduino
2. Between AKM and The wire
   1. Pros
      1. easier then 1
   2. Cons
      1. don’t know TBD

BOM: