| joy | Trackjoy GUS Tracker Song |
| jwf | Buzz Jacinth Waveform Audio |
| jwl | Buzz Jacinth Waveform Library |
| jxx | Yamaha SY77 Audio Data |
| k25 | Kurzweil K2500 Data |
| k26 | Kurzweil K2600 Data |
| ka1 | Kawai K5000 Patch |
| kaa | Kawai K5000 Patch |
| kar | MIDI Karaoke Song |
| kat | Katorzer Music Composition |
| kdt | Konami KDT1 Song |
| keyboard | Amaya Keyboard Configuration Data |
| kfn | KaraFun Karaoke File |
| kft | Korg T1 Wave Data |
| ki | Klystrack Instrument |
| kit | NI Battery Drum Kit |
| kmp | Korg Trinity Keymap |
| kmp3 | TKaraoke Karaoke MP3 Audio |
| korg | Korg Trinity Sample |
| koz | Audiokoz Music |
| kr1 | Kurzweil K2000 Split Data |
| kr2 | Kurzweil K2000 Split Data |
| kr3 | Kurzweil K2000 Split Data |
| kraw | BRSTM Audio Stream |
| kris | Kris Tracker Format Song |
| krz | Kurzweil K2000 Data |
| ksc | Korg Trinity Script |
| ksd | NI Kore Sound |
| ksds | NI Absynth Kore Patch Format Sound |
| ksf | Korg Trinity Sample |
| ksm | Ken Silverman Music |
| kss | MSX KSS Audio Data |
| kt | Klystrack Music |
| kt2 | NI Battery 2 Drum Kit |
| kt3 | NI Battery 3 Drum Kit |