Preventing spikes when plugging jacks
Generally speaking, the problem that you describe is often easily cured by adding a resistor in series with the signal.  Resistor value is dependent on what the load impedance is but is often in the range of 22R to 100R.  

Higher value is better but the tradeoff is the voltage drop caused by that series resistor and the load impedance.

The series resistor does two things:

1) limits peak current during short-circuit conditions.

2) minimizes the chance of latch-up if there is significant ground voltage difference between the two devices being connected as you are plugging one device into the other.

It won't cost you anything to see of that helps or eliminates your problem.