That's worth a try, if only for the education. Still, the reason for putting the LS50s on top of the subs is to have each sub work in cooperation with its main. The sub under the left speaker plays the left channel; same for the sub on the right. I can see on the SHD output display that power on the two sub channels varies; they are not the same at any given time. And I can hear the difference. So I would rather find some other way to correct the low frequency nulls.
You could not differentiate the sub Left and Right output below 300 hz. There is no directionality to discern each channel. Case in point is my systems
woofer towers. Does the Left column sound different to the Right? I honestly cannot tell. I would have tried to move one of the towers to the back wall, but 30ft is a stretch with the servo cable being 8ft long. Play with the room sim and see what happens to the nulls.