If I have tracks from various sources and amplitude how can I normalise the amplitude when burning to a CD
You can't - you have to sort your file levels out first before attempting the burn. CD burning is a straightforward process, and the only thing that will be altered at all during the process is that any file that isn't 16bit stereo at 44.1k will be converted to this format, because that's the only one CD's use.
Using Normalize will get the peak amplitudes in your files to be the same, but it won't normalize the actual loudness (or 'volume' if you like) of the files, which depends on several other things, and it's very subjective. Personally I do this by ear because of the subjectiveness, but there is a tool in Audition which will attempt to do the task for you. Rather than go through it all here, have a look at the 'match volume across multiple files' section in the on-line manual, page 60.
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