... are manufacturer, professional amplifier. 1,250W 2,USB playing, radio station. SD card. 3, 70 ... record at MP3 format.2.Connect PC with USB interface, doenload and update music freely.3.Play ... power supply 5 seconds in advance, provide adequate warm-up time for amplifier or other equipments.4.Power ... etc.... We are manufacturer, professional amplifier.1.250W2.USB playing, radio station, SD card.3.70/100V ...