The acoustics of the main opera house of Turin, the Teatro Regio, had been challenged since the first opening of the theatre in 1976. The singers had pointed out difficulty in hearing the sound from the orchestra pit correctly. For this reason, the opera house was refurbished in 1996, in order to improve the balance between the singers and the orchestra. The aim of this paper concerns the detailed analysis of the acoustics of the main hall, called "Sala del Lirico", before and after the refurbishment. This analysis has been carried out by means of simulations based on a detailed acoustic CAD program. Furthermore, the performance of the new hall (1996) has been described by means of a large in-field set of measurements. In particular, the analysis of the simulated and measured acoustical parameters, shows how the acoustics of the new hall have generally improved, but have been affected by a significant reduction in clarity of the singer's voice for a large central area of the stalls. Even if the original issue related to the stage has been solved by the refurbishment, a new shortcoming related to the Clarity C80 distribution has been detected in the new hall.