High Sound Quality: Built-in a DAC(Digital to Analog Converter) with excellent decoding performance. Aluminium alloy shell reduces and shield outer interference effectively to ensure the sound quality.. Surface Craftsmanship: Sand-blast, wiredrawing, oxidation and laser engraving, never fade like paint spraying.. Excellent Output Performance: SMSL M6 can connect any headphones with high or low resistance.. Multifarious Functions: SMSL A6 is not noly a digital amplifier but also a headphone amplifier and it has DAC digital to analog conversion function. Come with a remote control for easy using.. Input Ways: Support USB/Optical/Coaxial Input. With asynchronous USB input(32kHz-384kHz).