Big ++1 for @millercarbon and others. The room is a HUGE problem, especially if your room is not on a basement or concrete slab. I had a 15x15 room on the second floor, and it was an absolute bass NIGHTMARE!!! Fortunately it was a temporary residence and I've since moved my system into a dedicated basement. Complete night and day difference!!! When I was in that wretched square room, I moved my speakers (medium sized 2-way floorstanders) 6 feet into the room and still couldn't alleviate the dreaded bass hump you're probably experiencing. If I'm you, I absolutely heed the advice of others and get some bass traps from GIK, or if aesthetics don't allow for this I'd seriously consider getting some bass management from the likes of DSpeaker, etc., or an amp with room correction like a Lyngdorf or maybe the new Elac integrated. In any event, you have my deepest empathy, and whatever you choose among these options, by all means do SOMETHING other than just changing speakers. You'll just end up driving yourself nuts and probably waste a lot of $$$. Best of luck in taming this beast.
