I'd be skeptical you'll find damping horns in this way to be satisfying long term, band aids like this usually expose their flaws over time. I don't see issues with your equipment so I expect upgrades to crossover only would be good starting point.
I have Khorns, tried the mat thing, totally unacceptable to my ears. My extensive mods are extreme, but have paid off handsomely in long run. Not saying you need to go this far, just go for some crossover upgrades and see where your at at this point.