Nagra DSM professionnal monitor 2 way loudspeaker system with removable battery box and microphone preamplifier. Specifications. Type: 2 way, 2 driver loudspeaker system, Frequency Response: 60 Hz to 15 kHz, battery/mains powered 15 watt amplifier, Dimensions: 320 x 130 x 240 mm, Weight: 6.3 kg.