My current space doesn't allow for me to have every speaker the same distance from my listening position. My receiver allows me to input distance by the half foot. My question is how exact do I need to be when putting in the speaker distance into the receiver. For example, my surround right speaker is 7'6" feet away from my head, while the surround left speaker is 8'1" away from my head. Should I round off to 8 feet for both speakers?