Es9023-USBDAC with good looks and connotation

Foreword:
       This is a small, beautiful and connotative Es9023 USBDAC. It uses the best-performing decoding chip in TI's PCM27xx series - PCM2706 for USB decoding and output I2s digital audio signals. The DAC part uses ES9023, which uses SABER digital - Analog conversion technology combines the best sound quality with high cost performance, and you can find a suitable aluminum alloy shell for it at Lihua, the price is only 1.8RMB.
 
Circuit analysis:
       The PCB is a 4-layer board, designed by Lichuang Professional Edition. The components should use basic libraries as much as possible to facilitate SMD patching;
       the USB socket adopts Micro USB for the adaptable shell structure, USB signal lines are differentially routed with equal lengths, and TVS electrostatic protection ;
       Digital and analog separation, each uses a high PSRR LDO to provide 3.3V power supply;
       PCM2706 is configured as I2s output, and a 30ppm 12Mhz passive crystal oscillator is selected due to volume restrictions;
       Es9023 uses standard official circuits, please note that the output capacitor is best to use Panasonic stickers film capacitor;
       the output audio interface uses a 3.5mm sunken plate audio socket.
 
Assembly instructions:
       There is a 370mAh lithium battery inside the aluminum alloy shell. Hammer the metal pins on both sides of the USB socket to push out the internal battery. Please keep the plastic support frame and LED uniform light disc.
       Cut the plastic support frame as shown below and install the PCBA. The LED uniform light disc is bonded to the reverse side. The indicator light uses a reverse-attached 0805 green LED (ordinary 0603 LED can also be reverse-soldered).
       Provide 3D printed parts to cover the audio output.