Need at least 900wpc in 4ohm

http://www.atma-sphere.com/

Remember the impedance, most us don't know what size room the OP has. There are other very fine speakers that work best with an abundance of available power too. Furthermore, there are a lot amplifiers available to choose from that can fulfill the demand. The final result is what matters.

Atmasphere to this day I consider the sounds I've heard emanating from Thiel CS 5's in appropriate rooms with their 2 Ohm load amongst the finest I've ever heard. Now, I didn't actually measure the output of the various amps that were being used on them as they were playing, but I'm confident that sound that came from the higher powered ss amps sounded better in part due to that extra power, and furthermore I think it quite possible that in these large rooms that there were times that those speakers might have been drawing 500+ Watts. You can't convince me that what I heard wasn't musical. I suspect that there might be other Audigoners with similar experiences. Perhaps some Apogee aficionados would care to chime in?

I disagree with Atmasphere's assertion that there are no particularly musical amplifiers that provide in excess of 500 Watts into a given speaker.

If the first Watt doesn't suck, why stop?

Choose your speakers, then the appropriate amplification.