Too Much Power

with speakers rated at 900 watts and have little concern about over powering or damaging them

You have a home audio speaker that can take 900 watts?

are the drawbacks to that much power?

Size, weight, heat, and if the gain values are high perhaps a little noise but quality amps are very quiet today. 

I was answering what sounded like a more general question. 

Plus one @fsonicsmith 

@stevewharton  Wow. I had not seen that before. That is quite a claim. Not sure I'd want to test that claim. Thanx for the reply.