Hi Andy,
Welcome to the Omega AudioCircle. You have a nice amplifier. The Alnico based speakers (XRS & Monitor) are in a completely different league than the RS5 based 3 series. To my ears there is just no comparison. The Alnicos have a flatter frequency response, are smoother, have a more organic midrange, and dig deeper into a recording without having an artificially prominent top end. My Alnico Monitors have some of the best bass I've heard and are run with a Decware Super Zen in a 13' x 17' x 8'H room and I have all the bass I crave.....without sub.