3 feet is okay. The most important thing is how do they sound to you? There really isn't a right or wrong. Do you have your QS8's mounted or are they on stands?

My QS8's are on stands so I have tried them in a lot of different positions. I've settled on a position off to the sides and slightly behind where I sit as the best sounding in my room. Next week I'll probably change my mind and move them again