The larger floor standing speakers are all 4ohm rated. You really, however, need to look at the graphs to understand the power requirements. If you run a set of subs and do major bass management then you likely are sending most of the power sucking bass to the subs offloading it from the mains.
I have a set of Axiom ADA1000 amps, so they do have a pretty good dynamic headroom on the amp. But I am also powering the largest LFR1100 speakers that Axiom makes. I know that Ian has said that to get the best performance out of these speakers, use the largest amp. I just have the hardest time wrapping my head around how much power you need in a day to day application.
I understand how a speaker works. The wattage from the amp creates the magnetic field in the coil that either attracts or repulses the coil from the big magnet at the back of the speaker driving the cone in and out. The cone has a mass and the faster/further it needs to move requires wattage. The power requirements are not continuous and dynamic peeks can be very high. But how much overhead do you really need?
It's a few thousand to buy a new ADA1500 and trying to wrap my head around if its throwing money against the wall and hoping that it sticks, or if you can and will get some form of audiable improvement or difference to the sound you are getting?
I believe the question has already been answered, however, it all depends on how loud your listening preferences are, the speakers you are using in your set-up and, of course, the size of the room. Keep in mind that doubling the power rating will only give you approximately 3-4db in additional headroom.
For reference purposes, my room is 27' by 12', my system is 9.2 with 3 powered subs. My three channels across the front consist of a VP180 and 2 M80s in a L/R configuration. I am using a Yamaha Pre-Pro with TWO Outlaw 150 w/ch. multi-channel power amps. I have considered in the past replacing them with a more powerful version of the ADA models but considering the price that would be paid and the fact that I currently can turn up the volume well beyond what would ever be normal listening levels and still have a perfectly clear sound, for me, there was really no point. Of course, both amps are a few years old and out of warranty so if one or both of them die, my thoughts about it could change.
Of course, with electronics we are always looking for that "holy grail" in sound so the old adage of marketing and sales takes over in our mind. "Sometimes we buy what we want, not what we need".
