I am having issues when I use non-grounded devices (like my laptop, or my flat panel monitor) in my system. Ostensibly, both are \'grounded\' in that their power supply transformers are grounded, but the wire going into each has two leads. When I do this, I get an information-rich electronic hum in my audio. it happens, for instance:
When I plug my laptop Indigo card feed into my mixer. If the laptop is running off of battery, I don\'t have a problem.
When I use my flat panel monitor with my desktop DAW. This does not happen with my CRT monitor, same brand (Viewsonic), etc. The noise is again \'information rich\', in that it varies with what is going on on the screen.
I suspect that this has something to do with different reference potentials, or induction in the absence of grounding, but I\'m not sure and I don\'t know what can be done about it. Any help would be greatly appreciated!