Re: Interference or bad amp?

Hmm, Ok new guy is going to give this one a crack. From what I gather it is both monitors getting the hum. You have tried a humbuckler, ground lift etc so it is likely not coming up the ground from the wall. The reason I mention this is that I can think of two situations in 10 years that fit this scenario. The first was a shoot where a dp had plugged a consumer grade monitor in to his camera out and the wall. The power leaked (for lack of a better term) Up the ground wire through the camera and back into the mix. Which we realized later is why we only heard it when tape was rolling. Point is start checking the weird stuff I would take a ground lift and start with your monitor and start hitting every peripheral attached to that station until you find it.

Ps. An engineer friend later told me that while most broadcast and industry equipment has shielding against this type of thing it is not always the case with cheap or consumer grade stuff.