Nothing in music is ever simple...
First point is that the Yammies are rated at 500W Peak power - not continuous or RMS. RMS (Root Mean Squared) represents an average level of signal over a period of time, and hence will be lower than the occasional peak, and therefore speaker RMS ratings will be lower (typically a half to 2/3) of the peak rating. So if you put a continuous, heavily compressed or limited 500W into one of those speakers you would turn it into a flower pot.
On the other hand, you can run into trouble running an amp at its full rated power - different people have different and forceful views on this, but in essence an amp running at max is liable to clip, which sends a highly damaging signal to the speaker, again adding to your flowerpot collection.
So the answer is to buy an amp which is at least up to the maximum RMS handling of the speakers (with those Yammie probably 350 Watts per side, 700 total, at 8 Ohms) or greater, and listen carefully for any signs of speaker distortion as the volume goes up.
Some bass players regularly run power amps rated much higher than the cabs, which gives them a clean signal and pushes the speakers up to the volume level where they operate best.
Hopefully some more erudite posts will follow this.