Not particularly in my experience. I had an old 2ch receiver back in the day (70s) and moved up to separates (i.e. separate tuner/pre-amp/amp boxes) and while I tripled my power, no other significant difference in SQ nor when I moved on from that setup to my current batch of avrs (and I still use some of that old 2ch gear). The changes were when I moved speakers to different rooms/houses, and the speakers themselves. There's a lot of generally baseless chatter on the net from 2ch gearheads on the subject IMO, though
Some of those guys hear differences in cables, too.
As was pointed out, perhaps looking at your room/setup now in detail would be the best first step, to maximize what you've got. You've got good stuff....