"DJC" wrote:

MP3 is lossy, the compression removes detail you can never recover.

Oh sure, I appreciate that. But I was concerned about subsequent copies
mp3 - mp3. Does the quality (compressed though it be) remain constant?

For editing you need a lossless format, WAV or FLAC or €¦?

Some of the files I'm working with are m4a which isn't a format I was
familiar with. Where do they stand in the quality hierarchy? Better than
mp3?