I can't. I swear, it has never been loud enough to be noticeably detectable, and I am thinking I need to take it in and have it checked out. These days, I can't even tell when I've turned it on or off. I realize there is a little lag time between hitting the button and actually hearing results, but it just ain't happenin'. This morning, I faded all the sound to the rear, hit the sub button, nothing AT ALL! No difference in sound whatsoever. Anyone else having problems?