Audiotomb has it right on suggesting the 2 inch change then do a sound check process. When the speakers were along the long wall you probably were at a reinforcining node (the bass is a wave function that adds at subtracts). Putting the speakers in, or near the corners usually increases bass. With the speakers 4 to 5 feet out like you have them you have avoided this reinforcement. The same thing will happen if you experiment with the long wall placement. Since the short wall placement puts the speakers closer to the side walls you are probably getting more first reflections reaching the listening position within the time frame where the brain hears them as coherant parts of the music. that could be causing the brightness/harshness. On the long wall the first reflections reach the listening position much later. I have my speakers on the long wall. There is a glass door on one side about 5 ft from the speaker and a glass bay window on the other about 8 ft from the speaker, both without treatments, and the first reflections are not unbearable. Treatments would be better but there is the WAF.good luck