Yes one would be remiss to not think of this, and I have a few times, but ideal sound reproduction is simply that we we have a waveform drawn of the air pressures at the original recording, and throughout time we are moving along this wave, converting its highs and lows corresponding pressure levels in the atmosphere at the precise time through the speakers. If a loudspeaker jumps the gun and moves faster than the signal wave, and sound pressure raises quicker than the signal wave, then it won't reproduce the original recording, it will either square the wave off (distortion) or if it oscillates, the wave is simply a higher frequency than the original. This is assuming we are using the pixels individually or simultaneously, however, owing to the speak of manipulating a wave-front, the simple explanation above is unlikely what is happening...
...so we move back to the Mexican wave theory to see if firing pixels faster than normal could work. If we are firing all pixels in a Mexican wave, and each is super fast, it's possible that each pixel can induce air around it to move (I spoke of this in #5), but this air has to come from somewhere, ie. to create a high pressure zone, you'll need to create a corresponding low pressure zone around it, sucking the air out, so what you're effectively doing is taking air from its adjacent pixels before it fires, reducing their pressure, so all adjacent pixels going to be firing from a negative pressure position (inverse square of distance I imagine), and won't be able to create the same pressure the first pixel did when it fired, nevertheless when subsequent pixels do fire, they will create some positive pressure, but then this chain continues and they suck air from their adjacent pixels. It makes their job easier but, then they aren't really doing work. Just imagine you have a car to push and someone next to you pushes harder, you might be strong but your strength isn't required to push. In the end we can't jump ahead of the waveform no matter how fast we move things. Like I said in #5, to create pressures at the high amplitudes of low frequencies you need to move large volumes of air, however to move sufficient volumes using "fast pistons" and inducement, Audio Pixels would require venting to allow drawing additional air through the apparatus. I don't see this.
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