ES 3323 II is a mixer-amplifier with 4 mic-line audio inputs on removable connectors (the first input also has an XLR socket), CD/USB/Bluetooth – MP3 player and tuner and an aux input for an additional external music source. The amplifier nominal power is 320 W, available on 100 – 70 V constant voltage output (for loudspeakers having 100 – 70 V transformers). The 3 PAGING buttons on the front panel can be used to select zones to be paged by either the channel 1 or 4; The 3 MUSIC buttons turn the music on in the respective zones. As (optional) system expansion, it is possible to link a second generic external amplifier (delivering enough power for all loudspeakers, i.e. RCF UP 2321) to keep the background music in the zones that are not paged.