Power go out on the autotune? Power is more likely to go out on the mains than on the outboard, and no large show is happening without those.
You know that the stage flash and gimmicks of Iron Maiden are partly what Spinal Tap is mocking, right? They are not known for the quality their music, but for their bombast in both the music and the stage show. Many acts will play with a single dim light and sit down in some chairs and just play their songs. Iron Maiden brings out lasers, fog, sets, costumes, pyrotechnics; they are an Insane Clown Posse antecedent. Iron Maiden's only number one was called "Bring Your Daughter to the Slaughter" which became famous almost solely for its shock value.