The lower chart compares them with the same amp, same signal, same setting. The subjective result would be that the Earthquake would sound much thinner, with the volume significantly reduced, compared to the stock driver with the stock amp. In order to take advantage of what the Earthquake can do it needs a lot more power, and you'd need an amp that allows separate volume control over the woofers relative to the other speakers.
People who say that the Earthquake improves matters with the stock amp are succumbing to sighted expectation and placebo effect. The science is never wrong, whether you understand it or not. That doesn't mean that professional acoustical engineers like myself don't listen to the results, that is after all the entire point. But knowing the science allows us to take sighted expectation and placebo effect out of the equation.
Reading SPL charts isn't at all difficult.
http://www.centerpointaudio.com/HowT...onseGraph.aspx