Soundcraft 8000 Master channel noise issue

[Tonealive]

Thanks Jensenmann... ok, I just tried that and still the issue. It has individual 1/4" ouputs for each send and return for each channel. I tried it with both a TRS and TS cable, in various stages of not being all the way in.

[Tonealive]

So does it seem like this is an issue that would require the master channel to be serviced?