The number is 57 from what I heard a couple months ago from my buddy, Kavtor. Seems like you've already started there. I'd be tempted to get some results with 56 just to see if one can produce a Parry, but I'd be more interested to see a Parry at 57. (cause from what I've read... not happening)
Anyway I'll try to dig up the source, I'm sure he said it was EJ where it originated from.