The proper answer to this leading question is, of course, DUH! Everybody wants their sound system to sound better than it does, even if, by comparison to other systems, it sounds pretty darned good. So how does one accomplish this? Easy - start from scratch again.
Now I can almost hear the blood beginning to boil in readers with short fuses - "How dare you tell me to 'start over' after all the time and effort I've invested in my current system?" Calm down, I'm not suggesting you sell everything and begin with all new components - no, what I'm suggesting is that you remove all your electronics, cables, and assorted audiophile dodads from your listening room and then put them back into place again.
Now you may be thinking, "What good does taking everything out and then putting it back in do for me?" What it will do is clear away the cobwebs (literally and figuratively) and allow you to think about what really is the best way to configure your system.
And what will all this moving and thinking accomplish? At worst it will allow you to better position your cabling (and while you're at it giving each male RCA connector a wipe with a clean cloth) so that it will be less of a rat's nest. You may even find a way to route your cables so that AC power lines and signal cables don't run parallel to each other (it's much better if they are separated and if they must cross each other, they do so at an oblique angle.)
When I moved from my old room in my old house to my new room in my new house I spent a lot of time thinking about where things would go so as to minimize the native negative sonic characteristics of the new room. And while most of us do some degree of optimization when we first move to a new listening room, many audiophiles don't change much, if anything, in the room as time goes on. The problem with this is that eventually most listening rooms, if not culled through occasionally, become too full of stuff for the best sonic results from the gear you have at hand.
In point of fact MOST listening rooms I've visited that have been in place for more than five years have too much stuff in them to allow for optimal sound. And as much as I hate to admit it, some older audio reviewers have the most cluttered and disfunctional listening rooms I've seen. There's no reason to name names, but when it gets to the point where you have no room to move your listening chair more than a few inches because of equipment racks and media storage, you definitely have too much stuff in the room.
We've all heard the cliché, less is more, and sometimes it's even valid, especially when it comes to the amount of audio gear filling up your listening room. Lighten up! Your ears will thank you.