I owned 3A sigs for quite awhile. When I first received them I was working on a project in Dallas and set them up in the little condo the company rented for me. There was only enough room to set them about 2 foot from the front wall and the couch was probably about 6 feet from the center of each speaker. It wasn't even close to enough room for them.
Once I got home and put them in my normal listening room I found that they sound best when you can sit at least 8 feet from the speaker. Plus they need to be at least 4 feet from the front wall and, of course, you want space behind the listening position. I would think that for them to be at the best that the minimum length of your room should be 16 feet.