The Cayin C5 is a portable amplifier with a generous amount of technology cultivated in vacuum tube amplifiers. ■ Carefully tuned sound quality C5 features a classic circuit design and carefully tuned sound quality. The exquisite circuit design of the opamp and buffer is engineered to balance high performance and durability. ■ Use as a mobile battery: The built-in C5 battery can also be used to charge your other mobile devices, and it can also be used as an emergency battery when you are on the go. ■ Adopts high grade parts • Adjust to your preferred sound quality • Not only is it a technology to guarantee superior sound quality, but also a lot of selection of parts are incorporated into each piece. Uses LME49600 for the OPA134 high performance amplifier and headphone amplifier IC. We also select the best quality components such as WIMA capacitors, ALPS potentiometers, Ti ICs and more to ensure powerful driving and low noise reduction. The gain is high/low and the bass can be adjusted to your preference.