I work with audio electronics in the touring concert realm and I've been seeing a gross failure of a certain balanced line driver IC, the THAT 1646. Main symptom is no output and most common failure mode is the OUTPUT pins latching to the supply rails (-15V or +15V). I've seen both outputs at +, both at -, or one at each. Usually all other pins look ok but at times I have seen full rail voltage on the SENSE pins or a <10V on the INPUT pin. Most of the time the chip looks ok and shows no sign of heat but I have had a few that were giving off lots of heat.
It's not my business to know what's causing these failures but I am left wondering; whether it be inherent to the chip itself or the circuit surrounding it. Often the equipment is simply the THAT 1646 feeding a passive filter and suppression diode into XLR jack. Are these chips prone to fail on their own? Do they need extra "outside" suppresion and protection from the abuse of plugging an XLR plug in? In addition to the clamping diodes already present.