XLD Log File [Transcoding]

I searched around on the subject but didn't see anything…and I know there are lots of XLD fans here so…

Is there a reason why XLD will produce a log file when ripping a CD to .xxx format BUT when transcoding .xxx format to .yyy format there is no log file created? In other words how do I know the transcoding process is as pure as the ripping process? Is there some mathematical equation that essentially guarantees that once you have an error free digital music file that it cannot be harmed if you transcode it to another format?

For the record I am trying to convert about 40GB of ALAC (archived) to AAC true VBR @ 105 target quality for iTunes...