... , audio(MP3) USB in 20W output built-in rechargeable battery SE-728UDFM Portable wireless amplifierSpecification:Output power20WT.H.D.<5%Speaker unit6 ... ,MP3 inputFrequencency range175MHz~276MHzPower sourceAC110V/220V,DC15V 1.2AHApplication:Our SE-728UDFM Portable wirelss amplifier is your best choice for:1. teaching ...