If you crank it up too loud, you will hear it start to get "fuzzy" or unclear (sorry it isn't so easy to describe), like when you turn something like a boombox or small wireless speaker all the way up and it sounds really bad. This is the amp "clipping" and can cause the drivers to heat up and fail. If you start to hear that, turn it down. The bad part is, it is not always apparent that this is happening because clipping can occur before it sounds so bad that it is obvious.