I did a lot of upgrades in 2015, in a new "man cave". When I got a new pair of speakers, got them "dialed in" to the room with just a few bass traps, the sound was just great! But when I added a pair of excellent subs, that last octave of bass has been really difficult to incorporate into my system. Over time I've added more bass traps and have most of the "boominess" out, but it's been a struggle!
In a lot of these threads people say without the room being treated
It's a waste of money to upgrade you're system. The problem is I don't think most people know how to treat their rooms. I really think it takes a professional to know how to treat a room. Sure you can play around with it if you like but it could also be a big waste of time and money. And I know hiring a person to acoustically treat a room can't be cheap. I wonder why more people don't discuss this subject and make recommendations on who does this kind of work. When I look at the big picture this makes the most sense.