There's a wiki entry on this that explains the process. I'm going to give you my version, which is really, really close. Here's the wiki entry:
https://wiki.jriver.com/index.php/Re-Rip_and_preserve_tagsThe "big idea" that makes this easy is making the file names simple. Here's what I normally do:
1. Disable auto import
2. Get the new files for an album together in a directory OUTSIDE of MC's auto-import, and name them so that they only have the track number as their name. For example: 1.flac, 2.flac, 3.flac, etc.
3. Go to MC, find the album I want to replace, and rename the files so that they only have track number as their name. Same as the files that are going to replace them. That way the new ones just overwrite the old ones! I use the Rename, Move, and Copy tool to do this. Just use the Filename section to rename the files as: [Track #]
But, if you're replacing the files with a different format, you'll want to change the existing files to have the NEW file extension. An example will probably help:
Old file name: 01_Speak To Me.mp3
New File Name: 01.flac
Rename template:
filename:
Rule: [Track #]
Find & Replace:
Find what: mp3
Replace with: flac
So, you'll end up with file names that match the new files that will be replacing them! Makes things very simple.
4. Drag and drop the new files into the directory with the old files. If you've done the above correctly, the new files will replace all of the old files, one for one.
5. Tell MC to read the tags in the new files: Library tools > update library (from tags)
6. Tell MC to write out any library tags to the files: Library tools > update tags (from library)
7. So now you're pretty much done, except that your file names only have track numbers in them. So run rename, move, and copy again, but this time use your normal filename template to change the file name to whatever you normally do. For me this would be: [track #]_[Name]
Of course you should play a few of these files to make sure this whole operation worked correctly.
Brian.