I use Sound Check most of the time, but it doesn't work in some situations. Audiobooks usually end up with various volume levels over the different tracks. Gapless CDs are another problem. If Sound Check decides to make track 1 louder than track 2, and the end of track 1 leads into the beginning of track 2, there is a jarring volume change where there should be a seamless transition. For normal use for in the car or a mixed playlist it's great, but if I'm doing serious listening I turn it off.