This is how I solved the problem of standing waves with my M3s and yammie sub in my living room. I stuffed the sphincters of the M3s with foam. All issues disappeared without using any EQ.

I don't understand where he gets the numbers of 7 feet for speaker distance and 19 feet for sub distance. Those must be examples.
M100,VP160,QS10HPx2,EP800,M5HP,M3,M50 v4
M80,VP150,QS8x4,EP600 v2
Air N2