In this paper we propose a Spatial Augmented Reality interface for actuated acoustic instruments with active vibration control. We adopt a performance-led research approach to design augmentations throughout multiple residences. The resulting system enables two musicians to improvise with four augmented instruments through virtual shapes distributed in their peripheral space: two 12-string guitars and 1 drum kit actuated with surface speakers and a trumpet attached to an air compressor. Using ethnographic methods, we document the evolution of the augmentations and conduct a thematic analysis to shine a light on the collaborative and iterative design process. In particular, we provide insights on the opportunities brought by Spatial AR and on the role of improvisation.