The present work concerns the acoustic design for a former church converted into a chamber music hall. The current status of the hall was classified with an acoustic measurements campaign according to technical standards requirements. Focusing on literature theories, an accurate sound energy spatial distribution analysis led to the development of an acoustic intervention, not-invasive from a volumetric point of view. An array of hanging reflecting panels over the musicians' positions improves clarity C80 and sound strength G trends giving to the church an acoustic quality worthy of a concert hall. All the acoustic treatments were validated using a numerical model, calibrated through the measured values, and an acoustic simulation software in order to estimate the effect of the whole improvement proposal.