Thank you for viewing. FX-AUDIO- DAC-M3J with B, bare board only, part ②. Operation has been confirmed. This is a device that connects to a computer or smartphone via USB to convert digital audio sources to analog for high-quality listening. It's USB-powered, so no external power supply is needed. It's a Hi-Res compatible DAC & headphone amplifier. To use it, you'll need a USB cable and headphones (or earphones). When connected to USB, a blue LED lights up, and it blinks while playing music files. Turning on the blue boost switch enhances the bass, providing a powerful sound. 【Product Features】 ■ Hi-Res support with VT1620A ■ Stable power supply, essential for bus-powered devices We've generously used audio-grade capacitors, exceeding what's necessary for stability, achieving bass performance unimaginable from such a small enclosure. ■ Philips TDA1308 is used for the headphone amplifier IC ■ with B!! Equipped with a bass boost function to emphasize bass, which can be switched ON/OFF. The authentic CR-type Bass Boost circuit provides a significant effect, with +6dB at 80Hz and a remarkable +8dB at 30Hz, allowing you to fully enjoy dance music and rock. 【Main IC Specifications】 ■ Audio Controller IC (USB-DAC): VIA VT1620A Supported formats: Up to 24bit/96kHz ■ Headphone Amplifier IC: Philips TDA1308 SNR 110dB, THD+N 0.03%, Output power 40mW(THD+N < 0.1 %)