Looking at the speakers in your OP photos, aren't the listening axis of those speakers going to be way above ear height?
Also, flushed into the wall like that will effect their sound, just so you know. Towers like that have something called a "baffle step" region right around 300hz. In that new wall mounted configuration, you should expect them to sound much more - full / warm - or thick / muddy - depending on if you like the new way they sound. Your receiver eq may take care of it, just giving you the heads up.