Actually, as I have said before, if you are listening in a 5-6-7 channel stereo mode you WILL need nearly all available power to all channels driven when listening at high volumes. This is about the only time I think anyone would ever need near full power to all channels, so this feature alone makes the all channels driven spec that much more important.
I found the integra specs a little confusing as on the side it states all channels, then in the specs it speaks of 2 channels driven at 8,6,4 ohm impedances, weird.