https://androidbrick.com/cayin-ru6-r-2r-usb-dac-review/
Cayin has announced its first USB Dongle DAC. The RU6 portable DAC/Amp features an in-house developed 24bit Discrete R-2R resistor ladder circuit that can decode up to 384kHz.
The hardware volume control buttons are backed by a sophisticated resistor ladder volume circuit, and users can select between Non-Oversampling or Oversampling mode through a simple menu setting.
RU6 has two headphone outputs, one 3.5mm and one 4.4mm balanced.