As mentioned, it depends on your room dimensions, seating distance and how loud (spl) do you need. There are online spl calculators that you can use to figure out your need.
In this case though, the answer is, adding an external amp won't make a difference because your speakers are only to handle 180 W peak, and your Yamaha AVR definitely can definitely handle 90 W average/180 W peak into 4 ohms. Regardless, please note that of the 3 amp you mentioned, 2 of them are not more powerful than you AVR anyway, not at all.