Anthem is an advanced open source MIDI sequencer. Anthem allows you
to record, edit and playback music using a sophisticated and acclaimed
object oriented song technology. It runs under the KDE desktop
environment, on Unix-based platforms.

It is based on the TSE3 sequencer engine and therefore provides a
great deal of power, combining the innovative object oriented TSE3
song technology with a simple, intuitive interface.

WWW: http://anthem.sourceforge.net/