I think there's something not working as it should but the above info would help immensely in testing.
Also, are you limiting the volume changes applied by the values stored in track_peak and album_peak? I'm suspecting it but I'm not sure.
Thanks a lot for looking into this.
PS
At the moment you are not clarifying how the player chooses between track and album gain. If you are doing it the "smart" way, I think it's better to be explicit about it and, maybe, leaving the choice to the user. I say this because while the "smart" thing it's really smart, it's not a "by the book" implementation. It was the result of several feature requests on Squeezebox forums. In case of mixed playlists it's really the only option that makes sense but still... people are special in wanting the one option you are not providing
