Hissing from Model 12

[BlueEagle]

When I plug in the headphones, it hisses. all faders down, all knobs set to 0. any idea what to do?
I just got it. Nothing seems out of the ordinary with the buttons.

Everything is also balanced normally with the knobs.

 

[Max Relic]

Welcome to the forum.
Please give us more details on how you set your Model, there are too many factors that could lead to unexpected behavior. "Balanced normally" tells nothing in itself.