match amp to speakers

ok here is my question. What is the proper size amp for set of component, or other speakers?? If the speakers RMS is say 100 watts.
should you go with an amp that puts out more than 100 watts, at 4 ohm, so the amp will not have to work hard and be able to drive the full wattage to the speaker?? Or should you use an amp that puts out just 100 watts??

From past experience I would look at max of the amp and the rms. The components will have a passive crossover that will eat some of the wattage while separating the frequencies. So I would use an amp with an rms a tad lower. Now you have to know if the rating is per pair or each set of woofer and tweeter. I may use an amp that is 100w x 2 max - 150w x 2 max. Then set gains lower so the amp doesn't have to work that hard. Check also the thd% on amp. Get a clean amp for your speakers to avoid noise that may discolor sound. .008 thd is very clean. Some Pioneer amps a few years ago had that rating.