This paper presents experimental results on the control of stochastic flexural vibrations in a plate equipped with five piezoelectric patches connected to self-tuning multi-resonant shunts composed by N-parallel resistive-inductive-capacitive (RLC) branches. The study contrasts the tuning of the branches based on the minimisation of the time-averaged total flexural kinetic energy and the maximisation of the time-averaged electric power absorbed by each RLC branch relative to the resonant responses of the target modes. Next, it investigates the online tuning of the branches RL components with an extremum seeking algorithm set to maximise the time-averaged electric power absorbed by each RLC branch.