Originally Posted by bigshot
I transcoded AAC 256 VBR ten times from AAC to AIFF to AAC to AIFF to AAC... etc. The difference between the original AIFF and the tenth generation AIFF was VERY small. Transcoding high bitrate lossy isn't really a problem.
I doubt that the difference between your MP3s is audible.
The .mp3 coded is VERY different from AAC. I would think multiple passes through .mp3 and back would fare much worse.
If you want to try something really wild, transcode between AAC > mp3 > AAC (different rate) > mp3 (different rate).
I found a set of conditions once, .mp3 > Dolby AC3 that actually sounded better than either alone! I don't recall the bit rates, but something about that combination was complimentary. I doubt this would happen very often though. It was in a broadcast situation, music stored on HDD as mp3 files, then sent over a Dolby STL to a transmitter site, about 15 years back. Unlikely this is an issue anymore.