Speakers do not 'blow' from too much power. Speakers are damaged by too little power; driving a speaker to volume levels which require a level of wattage greater than the amplifier can provide will produce 'clipping', which can easily damage a loudspeaker.
Clipping (audio) - Wikipedia, the free encyclopedia
The way to damage a speaker which is driven by an adequately powered amplifier is too go berserk with the volume - causing the loudspeaker to draw more and more power, play louder and louder until it physically fails.
The volume knob acts just like a dimmer switch for a light: crank it up and the bulb (speaker)
draws more power and produces more light (volume), turn it down and the bulb (speaker)
draws less power and produces less light (volume).