As another option in the audio analysis window, add a summed graph of all active audio channels. That would probably need to shift the Y-axis reference as long as it is active to get the scale away from classic FS display. But I guess getting a summed audio level for multichannel audio is still interesting. Maybe one could reference this to formal target SPL for cinemas based on the 85dB SPL(C) based calibration? e.g. yielding something like '108db SPL(C)'

On the other hand, the audio level display is already able to display positive above FS values. One still would need to think about the proper relation between summed and individual channels. As for individual channels, positive above FS will always mean clipping, and means a failure, while for summed output, not necessarily.