KMid2 plays MIDI and karaoke files to hardware MIDI devices or software synthesizers. It supports playlists, MIDI mappers, tempo (speed) control, volume and pitch (transpose) controls, and configurable character encoding, font, and color for lyrics. The graphic views include a rhythm view (visual metronome), a channels window with solo/muting controls and instrument selectors, and a piano player window (pianola).
KMidimon monitors events coming from a MIDI external port or application via the ALSA sequencer, or Standard MIDI Files. It is especially useful if you want to debug MIDI software or your MIDI setup. It features a nice graphical user interface, customizable event filters and sequencer parameters, support for all MIDI messages and some ALSA messages, MIDI playback, and saving the recorded event list to a text file or SMF.