I think you need a 1500-2, in bridged mono mode, for each speaker.
I dunno... seems to me that the 1500 amps unbridged occupy a nice spot just this side of "overkill"
While there's obviously no such thing as overkill, it's nice to be able to keep the complexity (and cost) under control. I'm trying to avoid a situation where I have to wear hearing protection in order to take full advantage of my system.