I am unaware why this isn't a more widely reported issue as one would expect if it is frequent, but the volume of Twitch streams seems rather low, regardless of creator, compared to, let's say, Youtube. Currently I find myself turning my volume to the absolute max to watch Twitch, forcing me to turn down all my other volumes, or get my ears blown off when I go back to gaming or listening to music. I am watching through browser (Firefox) and the in-player volume is set to max as well.