Sound loud and clear, high SNR, tested two 100W8 ohm speakers pushing very loud. Compact (PCB board 31x22mm), the circuit is simple, reliable work. Computer power available USB port can also be battery powered for any space, with LED power indicator can be observed at any time power status. Has sealed potentiometer with power switch, adjust the volume and control can be arbitrary and off the power supply; export grade 1000uF filter capacitor using a large capacitor, and all other components used in all genuine, long-term stability.