Anyone with even a basic knowledge of acoustics could have told you the same thing. What you did is create a diffuser, anything that reflects sound unevenly sending it off in different directions. Your room being fairly small the effect is greater. Because walls are closer together so all reflections arrive closer in time to the direct signal, and also higher in volume, than if the room were bigger.
If you think the improvement you get from panels and traps and stuff is good, wait till you try some of the really amazing stuff like HFT.
If you think the improvement you get from panels and traps and stuff is good, wait till you try some of the really amazing stuff like HFT.