Assuming your amplifier gain is set correctly and you're not using excessive volume and/or EQ boosts your speakers will handle the power. power ratings are one of the most misunderstood things about audio.
You can measure watts using a volt meter set to AC, 0 dB test tones and basic math. Please read this entire article before deciding if you want to do this, especially this part:
There are some problems with this method! This method should not be used to see HOW MUCH power your amp has when turned all the way up! The speakers will play so loud they could be damaged and your ears may not like it much either.