You can go on if you wish, as an installer of 15 years and feeling and hearing differences, 1 db has never been an audible difference. Then once i graduated from that to becoming an audio engineer and mixing and mastering music 1db increase in volume creates almost no change and is most certainly not audible. You can post quotes all you want to, i go by experience and things i have been witness to, not just what someone says in a book or a quote. We can just agree to disagree, i say 3db is the threshhold to hear a difference, you say 1 or even .5 db's.