@bob540
Wait — I thought shorts in electrical or audio cables or equipment is bad?! But they were the solution?
You don't want to short out a low impedance voltage or power source (an output) because it will draw high current. That's why people are saying to remove the center pin on shorting plugs for output jacks, as that turns the plug into a non-shorting cover that can't draw current.
But inputs are high impedance, and shorting them is safe and prevents stray noise from entering the system.