MOS-FET (Metal Oxide Semiconductor Field Effect Transistor), well known as a superior electronic transistor in home audio systems, is used in the final stage of the amplifier. Since MOSFET is a highly efficient element with a linear operation curve, it dramatically improves the S/N ratio in the high frequency range, which is especially susceptible to noise. This results in smooth and rich expressive capabilities, and sound reproduction infinitely close to the original source.