gapless Gtk-based audio player

 Aqualung is a music player for the GNU/Linux operating system. It plays
 audio files from your filesystem and has the feature of inserting no gaps
 between adjacent tracks. It also supports high quality sample rate
 conversion between the file and the output device, when necessary.
 .
 Almost all sample-based, uncompressed formats (e.g. WAV, AIFF, AU etc.) are
 supported. Files encoded with FLAC (the Free Lossless Audio Codec), Ogg
 Vorbis, Ogg Speex, MPEG Audio (including the infamous MP3 format) and MOD
 audio formats (MOD, S3M, XM, IT, etc.), Musepack are also supported.
 .
 The program can play the music through OSS, ALSA or using the JACK Audio
 Connection Kit.
 .
 Aqualung supports the LADSPA 1.1 plugin standard. You can use any suitable
 plugin to enhance the music you are listening to.