Hi,\n\nOur AV Technician at the school I work at recently left and I have been left with taking over maintaining the AV in our school. The problem is I'm the IT Manager and know next to nothing about AV.\n\nI recently had to make a change to the projector in the main hall and this necessitated a change to the way the projector connects to the speakers.\n\nThe sound comes out of the projector's 3.5mm audio out connector into a adaptor that connects to an ethernet cable for the run to the mixer box. The ethernet then connects to an ethernet to RCA L+R (red and White) adaptor. The RCAs connect to a pair of mono 1/4" jacks that go into the mixer box that has inputs from this and other sources including 3.5mm aux and wireless microphones.\n\nSince installing the setup the speakers now hum continuously when the projector is turned off, but not when it is turned on. I have been told I need a "DI" box but I have no idea what one is, what I am looking for or even one that supports an ethernet connection.\n\nMost of the setup was installed by the previous AV Tech so I don't understand it. I've just been lumbered with it.\n\nCan anyone help please?