Just so that other users know...
There are currently some problems with the interaction between WinampAC3 plugin and MusicBee, it may not work for you, whereas FLAC and WAV files that are DTS-encoded already work in MusicBee without the plugin, and you can download an AC3 plugin for MusicBee from the BASS web site at un4seen.com (use the exact same method as explained in the MusicBee FAQ for AAC).
Also, currently there is no way in MusicBee to bring up the Configuration dialog for any Input Plugin (which is not needed with Shorten Plugin or other simple input format plugins, but is needed for WinampAC3 plugin and possibly some others).