DJM-450 XLR White Noise

Hoping someone can help me troubleshoot this.

I have a DJM-450 hooked up to a set of monitors through the balanced master output (XLR). They hook up to a subwoofer first, then the monitors.

I'm getting white noise that remains constant in volume no matter the gain or master volume level. If the master volume is taken all the way down it turns off, but at about the first notch it comes on and remains at the same volume throughout the range. The channel faders do not affect it. Open or closed the noise remains.

Nothing else is connected to system so this is specific to the mixer.

Most baffling to me, the noise is not present on the cue outputs nor the unbalanced outputs. That last one I find pretty annoying.

I've tried hoking it up to different power outlets, isolating the cables, jumping the subwoofer, and maybe a couple more things.

I could get another set of XLR cables, but what are the chances that that's the problem? I also wonder if a surge protector might help, but doubt it that as well.

Any suggestions?

Thx!