| ki | Klystrack Instrument |
| kit | NI Battery Drum Kit |
| kmp | Korg Trinity Keymap |
| kmp3 | TKaraoke Karaoke MP3 Audio |
| korg | Korg Trinity Sample |
| koz | Audiokoz Music |
| 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 |
| kt | Klystrack Music |
| kt2 | NI Battery 2 Drum Kit |
| kt3 | NI Battery 3 Drum Kit |
| kts | KT-Tech Compressed Audio |
| kxs | Kexis Lossless Compressed Audio |
| la | Lossless Audio Compressed Data |
| laa | LucasArts AdLib Audio |
| latm | AAC Low Overhead Audio Transport Multiplex |
| lb | Low Bitrate Packer Compressed Audio |
| liq | Liquid Tracker Song |
| liw | Cakewalk Music Creator Chord Library |
| lme | LegglessMusicEditor Music Module |
| lmsff | Liquid Audio Player Audio |
| loas | AAC Low Overhead Audio Stream |
| lpc | LPC-10 Encoded Audio |
| lpc10 | LPC-10 Encoded Audio |
| lpcm | Linear Pulse Code Modulated Audio |
| lqt | Liquid Audio Player Data |
| lrc | Lyrics Data |
| lrec | Inter-Tel Web Conferencing Recording |
| lvp | Avaya Voice Player Audio |