In a multiuser scenario, the bit-loading, which has proven decisive in resource optimization for Power Line Communications (PLCs), has to be coupled with channel assignment to fully exploit its potential. Unfortunately, finding the most performing combination of channel and power allocation leads to integer (or mixed) programming problems, which are known to be NP-hard. To overcome the complexity of the resulting optimization problem, in this paper we propose an iterative solution that is able to guarantee both fairness and Quality of Service (QoS) to the users when the overall power consumption of the system is bounded and each subchannel emission is limited. This solution embeds a Connection Admission Control (CAC) that allows to leave out badly-connected users that otherwise would negatively affect the comprehensive system performance. Numerical results compare the presented resource allocation with the common greedy-based single user approach.