... ruler-flat frequency response; distortion levels very low.QA350 MOD V2 use good audio capacitors: Nichicon MUSE MP,Nichicon SILMIC, ... use several LDO, respectively offer power for: crystal oscillator, the main chip, the digital output chip, DAC digital, DAC analog, ... filter circuit strictly matches ESR to ensure minimum ripple output. Firmware can be upgraded, and the upgrade is simple.Provide external ...