I have a similar situation, having been the owner of M22s for quite some time. I'm in a bit of a conundrum though. I like to listen to music. The other people in the house use my system for HT. I can either upgrade my sub from a JBL PB12 to who knows what . . . or I can upgrade to a set of floorstanders for my mains. Something tells me I would be happier with the M60s + old sub than just a SVS/HSU/Axiom sub upgrade. I don't know the answer, but I wish I did???