Thanks Neil for your input.
Just for some additional info., the original audio is from a CD which I imported into iTunes, and I just used the default settings but I will now re-import as a WAV file.
I thought that maybe there was something wrong with the conversion, so I bought the same song from the Apple Store but the problems are the same.
I’ve been working on this project for about a month and hear the audio several dozen times a day. So I can hear (and see) every detail.
The overall audio is not that bad as such, but if you listen closely to the beginning of the second link you can hear that something is not right with the way the single piano notes are coming through on the export when compared with the original.
Something is either missing or there is some sort of an echo.
Anyway, I’ll try with the WAV route and would be thankful for any other suggestions.
Oh, any ideas why audio from iMovie export is fine but not from FCPX?