Let me give you specs first so you know what Im dealing with. Mac: OS 10.8.2 with FCP7. 10 Gigs of Ram Quad Core.
Never had this problem before. Im working on a project. Settings are Pro Res 422 LT 1920x1080 24Frames @ 48 Khz
Using exact footage to match settings from a Canon 5D Mark 3, all audio transcoded to 48Khz 16 bits aiff files.

If i play the audio files in the browser it plays flawlessly. Its as clean as anyone could ask for. When I lay it down on the timeline in FCP 7 all I get is cracks, pops and scratchy audio.
I have created AIFF files in Quciktime Pro, Compressor and iTunes and still no luck. I cleaned out my audio render folder and still the issue continues.
I have literally spent the entire god-forsaken day and night trying to figure this out. Its 2:52 in the morning and I cannot get this project completed because I can't even make cuts to the beats I want bc they are covered with distortion.
PLEASE!!!!PLEASE!!!!! Someone? How do I fix this???

This is what Im dealing with: Audio Issues on FCP Timeline on Vimeo

Weird problem!

What happens if you create a new sequence then lay in just the audio file without any video? - Let FCP decide the settings when you add the audio.

Are the video and audio files on the internal (system) drive or an external?

Tom,

I have had this problem if the audio is not at 48khz. Export your audio at 48 and then try again. Hope this helps. Oops just read that you did. Sorry no help here.

having a similar, and weird, issue. cut and exported a 3 min video to youtube for a client review. audio was clean. client asked for cuts which i made and posted the new video on youtube. now have discovered the popping scratchy audio. mine actually plays fine in the browser as well, and it plays fine if i export an aiff. tried putting the aiff in the timeline replacing the audio. nothing wrong. try exporting this configuration from timeline...new .mov features scratchy audio. btw this is a new issue, finished a project two nights ago and just doublechecked it, it's clean. hope someone has an idea, client needs the finished interview and i am out of ideas on cleaning it up!