3rd Iteration was rejected because the negative space was not creating something meaningful, thus not highlighting the usage of Gestalt's Principle of Closure.

Using the negative space as piano keys, the 4th concept evolved.

Added serifs to the previous logo for a more organic shape.

Incorporated another music instrument: Guitar, as a negative space element in this iteration.

Instead of taking only half shape of the guitar, this iteration has an inverted letter K which allows extra negative space to be created between both the letters.

Making the shape of the guitar more organic, this is the final iteration of the logo which was accepted. It has a proper implementation of Gestalt's Principle of Closure.