© 2017 Sissa Medialab Srl. All Rights Reserved. We present the latest results on the collision energy dependence of ?/s, obtained from a Bayesian model-to-data analysis of UrQMD + viscous hydrodynamics hybrid model to RHIC beam energy scan data for Au+Au collisions at 19.6, 39 and 62.4 GeV. Changes in the most likely value of ?/s over beam energy scan range suggest a dependence on baryon chemical potential µB. However, we also find the uncertainties regarding the value of ?/s to be notable at sNN = 19.6 GeV.