The main goal of this project is to address how the perceived spatial distribution of sound energy (sound diffuseness) affects the acoustic quality perceived by musicians at the stage. To that end, experiments of rehearsals with two musicians playing into real-time virtual acoustics scenarios are carried out. Sound diffuseness characteristics for each virtual scenario are set according to a strategic design of the experiment. The proof of the approach is challenging because the short path between the ear and the musical instrument of musicians requires fast processing for real-time purposes. The performances are recorded for further analysis. After performing in each scenario, the perceived acoustic quality of the musicians are collected through questionnaires. Using statistical and signal analysis, the performance of descriptors related to stage acoustics and sound diffusiveness will be evaluated. The currently available results include the proof of concept and a detailed analysis of the sources of uncertainty.