>>>Why on earth would anyone want 500 watts/ch? I don't care how big your house is, that is way, way more power than you could ever use (unless your goal is to go deaf!)<<<
500 WPC isn't so outrageous. I have had 400 WPC and with fairly inefficient Vandersteen speakers, they could go loud but not outrageously loud. I mainly have plenty of headroom for brief bursts with lots of bottom. 500 watts is only marginally louder. The loudness - watts relation is logarithmic so twice as much power is only 3 db louder so 25% more power is only slightly louder.
The more pungent question is what this amp really is. Cheap for sure. Reliable? Is it really 500WPC? Measured by what means? Will it have a noisy fan? There are other brands of high power amps that are fairly cheap (not this cheap) meant for PA use and those have noisy fans and dubious sound quality. They often also use phone jacks for speaker connections.