The ideation, conception and implementation of new musical interfaces and instruments provide more than the mere construction of digital objects. As physical and digital assemblages, interfaces also act as traces of the authoring entities that created them. Their intentions, likes, dislikes, and ultimate determinations of what is creatively useful all get embedded into the available choices of the interface. In this light, the self-perception of the musical HCI and instrument designer can be seen as occupying a primary importance in the instruments and interfaces that eventually come to be created. The work of a designer who self-identifies as an artist may result in a vastly different outcome than one who considers him or herself to be an entrepreneur, or a scientist, for example. These differing definitions of self as well as their HCI outcomes require their own means of critique, understanding and expectations. All too often, these definitions are unclear, or the considerations of overlapping means of critique remain unexamined.