I noticed that the music playback volume in MusicBee is much more subdued than in other players. Near as I know, I do not have any kind of graphic equalizer turned on or any other plugin that might affect volume. As an example (though this is not the only combo I tested), I played a track that I ripped from a CD to FLAC using MusicBee's built-in ripper. If I play that track using VideoLan VLC Player at 100% volume it sounds (subjectively) like 100% volume. If I play that exact same track using MusicBee at 100% volume, it sounds roughly like VLC's volume set to 70%.
I also tried it with an MP3 version of the same file, converted by MusicBee's internal converter: same results. Different files, different albums; same results. Windows Media Player, Miro, MediaMonkey...all play at VLC's volume. Only MusicBee is subdued.
I tried changing (unticking) the player options to "dynamically normalize volume of streams" and "normalize volume of tracks with replay gain tags" but neither of those did anything to change the playback volume level.
I should point out that as far as I recall, I did very little to no tweaking of the guts and deep options of MusicBee. I am a pretty basic end-user when it comes to this. I preset MusicBee to rip my CD collection to FLAC and always use the same settings since v1.4, I then use MusicBee's internal converter to create MP3 versions of the same files for playback in my car, and lastly, I listen to my FLACs using MusicBee. That's it. I'm not one to go messing around with equalizers, volume analyzers and what-not, but I will if the answer lies somewhere deep in that mess.