Maximum safe measured constant spl for sierra raal tower?

[Brannigan]

I was talking to my dad about how to calculate max spl for a speaker and he told me about how to calculate it by doubling the wattage for every 3 db over baseline sensitivity until you reach the maximum input power of the speaker but it seems like there would be more to it. Wouldn't the real max spl be limited by how high the lowest rated driver can go before the sound becomes distorted? Just wondering how high I can crank these babies before one or more drivers start to get speed wobbles or can't keep up with the other drivers. My amp is respectably strong but I'm too chicken to keep turning it up until they give. Can I do 115db (just guessing) actual in room spl like an imax theatre? I just saw the hobbit in imax and the sound was so loud it felt like it was punching me in the heart. Awesome If I'm doing my math right my 150 watt amp should be able to get the towers to 112db with 128 watts. Does that sound right?