I've been looking for numbers, but I cannot find the exact SPL for the SM-57. It's actually for a paper, so if anyone could help me out, I'd appreciate it.
They won't say, but a good guess would probably be around 141dB (+/- 3dB). That would probably be at the 5% distortion point. That's just a guess (but I'll bet it's damn close).
Max SPL for 1% distortion would probably be closer to the low to mid 130s dB level.