Juice Goose published an expanded application document for speaker protection.

Outdoor speakers mounted in stadiums, on light poles, on tops of buildings or on the ground have conductors that are effective antenna for high energy impulses created  by nearby lightning.  Damage to audio  components need not come from a direct strike. Lightning near an audio line can induce high current and cause catastrophic damage to equipment.

The LA surge protection circuitry features a hybrid, three stage design that includes fast acting MOVs, inductors and silicon avalanche diodes (SAD). This design guards against surges up to 5,000 amps with a response time of under 1 nanosecond and very low impedance of only 0.02 ohms. A gold plated circuit card mates with the PCB-1B base (priced and sold separately) to allow easy replacement of the protection module on a periodic basis, or whenever necessary following a significant lightning event.

 The LA Series of surge protectors is designed to protect two pairs of audio lines, each with a maximum 5 amp capacity. Current loads, up to 10 amps, can be accommodated by bridging the terminals and restricting installation to one pair of leads per LA module. 

The expanded application chart indicates maximum continuous audio levels of 300 watts at 4 ohms, 600 watts at 8 ohms, 300 watts at 16 ohms and 600 watts for 70 volt installations. LA Series surge protectors are available with clamping levels from 15 volts to 100 volts. The appropriate model for a given application is detailed on that chart.