The RMS power available to each LFR1100 using an ADA1500-4 is actually 750 watts. The total continuous output capability of the power supply is 1500 watts. Each amp channel can output 650 watts continuous. There are two amp channels driving each speaker so the maximum continuous output is being set by the power supply divided by two.
For an ADA1000-4 the maximum output of the power supply is 1000 watts continuous and each amp module is 250 watts continuous. Using a 6 ohm number for the rear the maximum continuous output available to each LFR1100 is 437 watts. Since the capacitance available for power storage is lower in an ADA1000 compared to an ADA1500 the dynamic headroom multiplier is also lower but it is still pretty good. Good dynamic headroom above the continuous power available is basically a matter that everything in the chain is capable of short bursts of power way above their continuous rating combined with the amount of capacitance available for power storage. The dynamic headroom is very important when considering your real-world overall power available for playing back a soundtrack.
Pretty soon I am going to change my system to have one ADA1500-2 driving each LFR1100. This will take the maximum continuous power available to each speaker up to 1200 watts (using a 6 ohm number for the rear) and double the dynamic headroom available to each speaker. The goal is to never hit the limits of the amplifier no matter the power being requested during the maximum dynamics of the soundtrack. And a good soundtrack will have very wide dynamics.