High Quality Content by WIKIPEDIA articles! Mixed In Key (also known as MIK) is Windows and Macintosh software that simplifies a DJ technique called harmonic mixing. The latest version of Mixed In Key analyzes MP3 and WAV files and determines the musical key of every file. Knowing the key, DJs can use music theory (such as the Circle of Fifths) to play songs in a harmonically-pleasing order. The software helps to eliminate dissonant tones while mixing songs together using a technique such as beatmatching.