Constant output noise Mbox 3 Pro

New Mbox 3 Pro. Constant noise goes from all outputs except phone outputs. I use balanced cables. Monitors: active Yamaha msp 7 studio or passive Alesis MK II. I tried different computers, different places, different studios. The level of noise always the same. If I connect something into input I hear nice input signal simultaneously with that noise. When I raise the output level (the biggest knob) I hear the noise with the same level. It is absolutely constant. I tried unbalanced cables and noise disappears! The cables works and soldered nice and works with other interfaces.