Very nice setup, Pogre. It's no Bose lifestyle system, but I am sure it still sounds very good.
I do think the black curtains complement the speakers and sub very well. Bye the way, do you have plans for any upgrades in the future, like Atmos channels? Another thing you can do is get a sub in the near-field, right behind you, if you have room. If you don't think that will make a difference, try it with one of your existing subs. Place it right behind you, firing right into your main listening position, just for a couple hours. After you do that, you will hate me.