As long as the speakers dont have paper in them, you should be ok.
I run Sony Xplod's - Not listed as "Waterproof" but have been completely soaked, no problems..
However, the Polk 521's are pretty damn incredible speakers.. If I need to change, Ill be going with them for sure. I just happened to come across these Sony's for nothin..
"Dear Fox News: I am writing today to request that you add a laugh track to your coverage to properly identify it for the comedy that it is.
Also, clown noses for the reporters would be nice."