Two combo inputs CH A (1-way XLR and Mono jack 6.35) are available in SA315, which can be switched between line input and microphone input. The audio port CH B(Mono jack 6.35 or a RCA port) is for the other sound resources like MP3, CD player, etc. There is 1-way signal input port for wireless bluetooth in it and the volume is controlled by terminal. The gain of CH A/CH B signal input is controlled by independent knob and 1-way master volume control knob. The four different audio sources can be parallel output with one-way XLR after mixed internally, and then sent to different speakers for sound distribution. SA315 can be installed by steel wire. It can also be standing by coupling bar or three-feet stand. The pole mount is 35mm. Various accessories are offered for SA315 to meet different kinds of installs #ACTIVESPEAKER #AUDIOCENTER #BESTSPEAKER #PORTABLESPEAKER #GOODSPEAKERS #ACTIVE_DSP_CONTROLLED_SPEAKERS