+1. Adding a sub will fill out the bass and then you can run the front left and right as small speakers with a higher crossover point instead of full range resulting in a cleaner midrange. Is the RC3 the timbre-matched center for the RB5’s? If not, finding the correct matched center for the L/R speakers will also help with clarity. I’m not familiar with the Klipsch center speakers. I did own RB5’s and Heresy II (not at the same time) and the RB5 were a better match for my room and system.