Spec sheets also show a 12dB crest factor being utilized for peak calculation rather than 6dB.
Lee
SRX900 Max SPL numbers are not calculated, they are measured using 12db crest pink noise and using the array preset for the Line Array boxes and the 80Hz preset for the subwoofers. Full-space for the array boxes and half space for the sub.
The SRX800 SPL numbers were calculated and the SRX828SP SPL number was calculated based on the Half-space sensitivity and peak power handling of the passive SRX828S. Given the peak power available in the SRX828SP of 2000w (33dB Gain) it has a theoretical Max SPL of 137dB while the SRX928S sub has a measured max SPL of 140dB.
Also the amp power is measured differently in the SRX900 as compared to the SRX800. The SRX800 stuff is 2000w Peak. For example the SRX828SP amp is 2x 750w cont. / 2x1000w peak.
The SRX928s amp is 1100w for greater than 1000ms and a burst power of 2500w for 20ms. This burst rating is not the absolute peak output of the amp but rather a shorter duration power number. This is the same type of spec that many 'elite" level power amp brands publish as the continuous power output of their amps. The true peak power of the amp in the SRX928s is more than 2500w.
Lastly..if you compare the actual frequency response curves of the 928S and 828SP, you will see they are basically the same and the 828SP doesn't really go lower if you are looking at the curves and the same preset info. The port on the SRX928s sub is a much better design and will produce more output down low when pushed hard as compared to the SRX828SP.