Low wattage amplifiers dont necesarily clip sooner than higher power amplifiers. Its the fact that the people using this low-power equipment turn the things up too loud and try to push the amplifier beyond its capabilities.
You will not damage a speaker with too low power as long as you are not clipping.
In fact, a low quality "high" power amplifier may damage your speakers sooner than a high quality lower power amplifier for one reason. Many manufacturers tend to over rate their amplifiers output and may actually be stating max output power using a clipped and distorted signal to attract buyers with the "Look how much power our amplifier makes" advertising.
The whole wattage and impedence issue is very much misunderstood by the general public.
I would write a post to summarize it, but I am lazy and I am sure Ian has probably done it here at some point.
