Can you ever have too much power?

Rogo - within reason you cannot have too much power. Amplifier-control of the speakers is one issue, headroom is another equally if not more important issue. My speakers are rated 100w/ch, but they consistently sound better with a 200w/ch amp, or more. Small amps, when overdriven, are what generally causes blown speakers. It is harder to damage a speaker by overdriving it with a big amp than with a small amp which is into clipping. If you occasionally like to crank it up then a larger amp is called for. If not then some of the issues raised above are indeed to be considered. I generally listen at only around 2w/ch, sometimes 20w/ch, sometimes more. At said 2w/ch level I have 100x that power level for an ideal 20dB of transient headroom.
Doubling or halving of power is a 3dB change, which seems like a lot but it isn't actually that much. Going from 1 to 2 watts = +3dB. 2 to 4 watts is +3dB. In the other direction, 100 to 50 watts is -3dB. 50 to 25 watts is -3dB.
for POWER:
1dB = 1.25x
3dB = 2x
6dB = 4x
10 dB = 10x
20dB = 100x

voltage (dBv) is measured differently however.