Peak voltage is 1.414 times greater than RMS, so always consider that when choosing capacitors. And there are some frequencies where LC peaking can raise voltage across some components higher than the source. A good example is capacitor C2 in the π Speakers two-way crossover. But 250V is plenty for the capacitors in a crossover like this.See the π Speaker Crossover document. Pages 68-80 show the voltage across each component in a π Speakers two-way crossover. The source voltage is 50Vrms (70Vpeak) and there are graphs for each component showing the voltage across them as a function of frequency.