With amps, speakers and subs you always need to focus on the RMS wattage, not the peak or max wattage. The RMS wattage tells you how much power a product can give or take without pushing the risk of frying anything.
So you you must match the rms wattage of an amp to the rms wattage of the speaker(s) or subwoofer(s) you wish to power.
With that being said, Ideally a 4-channel amp is used to power speakers. You need to purchase an amp that can provide 60 or so watts rms over each of the 4 channels of the amp because 60 watts is the rms wattage of each of your speakers.
I suggest the Alpine mrp-f250. It provides 50 watts over the 4 channels. I use this amp to power my speakers as well. It is great. You can find great deals on the amp on ebay.
I hope this helps and good luck!