Most of the IMAC planes are in the range of 92-100 dB, but they test at 25 feet not 9 feet.
According to the article on sound on the IMAC website, the equations predict that a 3 meter test will be 8 dB higher than a 25 foot test. However, these predictive equations are only valid for "ideal" cases. The real world measurements would have a lot more variability because of reflections from hard surfaces etc. That's probably the reason that ground tests have very little predictive value of in-air sound levels, when reflections don't make up a significant portion of the total energy received by the measuring instrument or your ear.