I agree with Mark. What you did should make no difference at all in the sonics of the system. Anything you hear is either signal processing or listening bias. Audiophiles get equipment crazy. I know that from personal experience. I've spent over 6 figures in audio gear over the years. There is nothing wrong with that as long we understand why we do it and what we should expect from it. I'd return the cables if you can. It is a shame to give a disreputable company like Monster any money at all.
