Let's say I have the cord inspector/magic glass thingy turned on.
For signal cords there should be a shortcut (key combo or double click) that does the following if audio is currently turned on:
Fade out audio
Make the inspector rectangle into a hslider, with range 0 to 1, set to zero
ramp up audio output for the selected cord with the hslider and send it to the sound card
turn the hslider red if values outside -1, 1 appear in the signal
fade out and remove the hslider when the user deselects the cord
fade in on whatever audio was outputting originally
-Jonathan