When troubleshooting audio problems, start from the source and make your way to the destination. # Check that Signal is Getting to the Channel Check that the channel is producing audio. Is there any activity on the meter? Could it be that If Mix A is not being Mix A is sourced Post Fader. If things aren't arriving post fader, the. most likely explanation is that things aren't getting TO the fader. If the signal isn't getting to the fader, even though it looks like it, it might be that you are looking at (monitoring) the signal that is going TO the computer. In split mode, the signal that is going to the fader is sourced FROM the computer. If ProTools isn't turned on and the right track with the corresponding DAW output isn't record enabled, there's nothing to send from the computer. If the channel isn't in split mode, the signal will still get to the fader because it doesn't require the signal to get to the computer first.