Developed from the recently emerged pre-coding aided spatial modulation (PSM) concept, a class of efficient receives antenna selection (ERAS) techniques are devised. Aiming at approaching the optimal RAS performance in context of the PAM system, we derive the upper bound performance of RAS-PAM in two different ways, by utilizing the condition number and eigenvalue and Wishart distribution feature for the channel matrix. Our performance results demonstrate that the proposed ERAS techniques are capable of effectively improving the transmission performance in comparison with conventional RAS-PSM systems.