A 300 watt solid state amplifier has the same power output as a 300 watt valve amp, it's the way that valve amps start to break up at their limit which makes them appear louder. A watt is a watt is a watt whether it's from a class A, AB or D or any other type of amp.
If you EQ a 250 watt amp with lots of lows (and hi if you want to blow the tweeter too) and push the volume too high you will hear what is best described as a farting/distorted sound. You may also hear a clicking sound as the voice coil bottoms out on the yoke (back plate) of the speaker. Square wave clipped distorted output from amps can damage speakers capable of handling many times more powerful clean (sine wave) signals.
If you hear farting or hard clicks from your speaker then immediately back off the lows and some volume. Once you've blown your first speaker it'll become common sense. My first (and last) was when I destroyed an 18" PA sub with a Sound City 120 and my Shergold Marathon bass back in 1977. Lesson learned.