... , the compass sou nd quality make people raised eyebrows 4,Stereo audio input and output,portable mini speaker easy connecting ... the 3.5 mm interface audio source equipment 5,USB power supply and the Nokia general lithium battery power supply ... response of Mini Speaker: 150Hz-18KHzS/N Ratio: ≥80dbAmplifier distortion: ≤0.2%Power input: 3.7V Outside rechargeable li-ion battery (Nokia ...