ISO Standard 23591 shows how the sound pressure level in a room can be estimated with the following two pieces of information: the sound power of sources in that room, and the sound strength G of that room as defined in ISO 3382-1. In an earlier study, the theory connecting room volume V, reverberation time T, and sound strength G was summarized, and a comparison of measured G to this theory was explored for a wide range of rooms. That test setup used Odeon software. In the present study, a different test setup is used implementing Dirac software to expand G testing to additional rooms of various sizes for evaluation under the same mathematical model. After a description of the equipment using Dirac software is discussed, a brief review of the additional rooms in which sound strength was measured is provided. Both measured and theoretical sound strength results are presented for these rooms. The difference between measured G and theoretical G using the mathematical model is analyzed statistically both for the Dirac test setup and compared to the results from the previous study.