Retiming MP3s

When I (legally!) rip some classical music CDs I have (especially operas) it rips them into separate files since they’re on separate CDs. I like to use a joiner to put them back together, but when I do, the timing still reflects the time on the first part of the file that was joined. Is there a way to adjust the time so it reflects that actual time of the entire mp3?

If nothing else pops up, you can rip your CDs to .wav format, splice them together with an editor, and convert that to .mp3. But it’s worth looking for other solutions first.