21 pc speaker system stereo pc speaker series logitech z colour black transmission mode cable analogue inputs 35mm jack input line in stereo rca input analogue outputs 35mm phone jack power rating 60 watt effective output 120 watt frequency response 50 20000 hz speaker system 21 system system active power supply mains connection signal noise ratio 80 db nominal impedance 8 ohm noise level 97 db suitable for smartphone mp3 player tv table