I'm not sure I disagree with any of the statments made above about "break-in" periods. However, I have noticed a change in the sound from my system during the first week or so after it arrived. Before everybody jumps on me, let me say that I was playing with cross-over cut-offs and the like, which may have had something to do with it, but, while things initially sounded kind of harsh ( a high frequency unmusicality) the sounded mellowed by the end of the week toward a sound I really enjoy.