I downloaded Audio Recorder. Upon playback of my first recording, a loud crackling noise was bubbling under my speach. I created a new user and made a recording and the input of my mac AL Book was CLEAN! Something in my administration user configuration is creating noise???? I used to make clean tracks with Digital Performer using the built in Mic. Now (I haven't tried it after many softwares have been installed) even in DP I am getting the same loud noise floor! Can anyone suggest why this is and how I can go about discovering the source of the noise in one user, and not the other?

When I was new to OS X I had a lot of crackling noises and such, for example every time I started playting an audio file, and glitches when I was recording. I don't know for sure if this is what fixed it, but it seemed to get better the first time I used disk utility to repair permissions. So I've been doing that about once a month since, and haven't had any more problems.