With the increasing number of initiatives concerning the design of new Digital Musical Instruments in the recent years and with the perceivable lack of methods for evaluating them, this work proposes a process for evaluating those devices considering the performer’s perspective. It also presents a case study which describes and evaluates its practical application. The proposed process could be also utilized as a very useful step when designing new DMIs, providing a structured tool for incremental development of prototypes based on user feedback.