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Agreed...15db peaks require 32X the power level, from Any reference db point. However, determining the actual power output and for a given signal input at a reference room measured db level will be a total function of the speaker systems efficiency (or, sensitivity..what ever, you know what I mean, hehe)!



You're right that sensitivity is involved in determining SPL but in this case we don't know the cubes' sensitivity. And we don't need to know the sensitivity either because we have enough data to solve the problem (see equation above).

By the way, since we now know the nominal power, we can figure out the in-room sensitivity of the cubes. We know that their sensitivity is 85dB/2.7W/18 feet for two of them. This reduces down to about 87dB/w/m for a single one.

Their efficiency is something else altogether. The cubes are 0.3% efficient at converting electrical energy into acoustic. The M3s are 1% efficient. For every 100W you pump into a cube, you get 0.3 acoustic watts out. The rest goes into heating the voice coil.