Quick question, when I am using the USB output send a signal for streaming when playing live, does the main volume effect the output volume of the USB signal or is the USB signal level coming from each channel?
It depends on what you have selected on the Soundcraft USB Control Panel on the Computer. It can come from either the main L/R bus-post master fader or the first two input modules. Generally you will want the main mix feed ( i believe this is the default choice but it's worth checking)
only soundcraft notpad will not work with master output, its only work with any of two input channels