1.Hot 4.1 amplifier speaker 2.4.1ch circuit design 3.USB,SD,FM function 4.OEM service 5. ... adopted in bass part, enable low-mid section fidelity clean and exquisite4.Wooden enclosure wholly made by hand, high intensity, effectively ... eliminate resonance and cabinet noise5. With Standby,Input,Menu,VOL+,VOL- keys on ...