This is an interesting thread. With previous boxers we fed what we thought were higher grade foods, eg. Eukenuba. Compared to some long haired dogs, shedding seemed minor. Saying that, the back of our fabirc couches were a favorite place to rub on, which they did constantly. We had to relentlessly vacumn them, or the considerable build up of hair would disgust any guest. I also recall an occasional cloud of hair flying around.
We learned the truth about food from this site, and have only fed Layla the higher grade foods. We do not suppliment. We are in Atlanta and she is an "indoor" dog, (as I hope most boxers are.)
Until this thread I hadn't thought about it. Layla rarely rubs on the couches and they don't need to be vacumned. She clearly sheds far less than our other girls.
I can't confirm this is because of the food, but seems to make sense. The better foods really don't cost that much when considering everything else plus the health benefits. I agree with others, try a very high grade food.