The rating I saw for the Polks is "250 W continuous power". Maybe I'm being misled but I take that to mean you can drive these at 250 W RMS indefinitely and they won't smoke.

The distinction between peak and continuous power is important because the difference between the two can be 10 dB or more in terms of level or about 10x in terms of power.

I agree with everyone else here that if you overdrive a lower powered amp, you can blow the tweeters even in robust speakers. I like Blackraven's idea of trying to get an amp that has good behavior (e.g. soft clipping) when overdriven.