Glen Sawyer - 2024-06-27

Yes, the 1.5.2 back end will work with the v1.2.5 or v1.3.4 versions of the GUI.

The menu "Options -> Tags -> Ignore (do not read or write tags)" will prevent all header changes.

The message by 2Bdecided (third-from-last message) in that "mp3gain is NOT lossless" gives a technical breakdown, but the short version is:
Most of the time it's completely lossless, i.e. the hash should be the same if you make a gain change of +N and then make a gain change of -N.
In some weird cases where it's not technically lossless at the bit level (hash is different), it's literally inaudible, not just "practically" inaudible. The mathematical difference is so small that not even your dog would be able to hear a difference.