1.Hot 4.1 amplifier speaker 2.4.1ch circuit design 3.USB,SD,FM ... 4.OEM service 5.VFD display New design 4.1 amplifier speaker 1.Hot 4.1 speaker , solemn and delicate overlook ... Standby,Input,Menu,VOL+,VOL- keys on the front panel. Output power20W+8W*4=52W Signal-to-Noise ≥70dB Driver units ... 6.0KG 20FT660 sets 40FT1380sets 40HQ1632 sets Hot 4.1 amplifier speaker with USB/SD/FM function and VFD display