I have never been able to get rear speakers to do anything for me. I've tried all kinds of speakers and types. One was 13 feet away and the other 11 feet. As you know, when I went from side QS8 to QS10, the difference was astonishing. Then when I powered the QS10 from an ADA-1000, that was another step up when I listened closer to reference levels.
As for your Yammie vs. a prepro, if your room is acoustically "good", then you may not hear a significant difference. I'm willing to bet though you have a low frequency-challenged room like the rest of us. When I got my Onk with Audyssey XT32, it was a huge upgrade. If you get a prepro with XT32, ARC or Dirac, you'll be in for a hell of a surprise. I hear ARC is much better than XT32. Your YPAO calibration is frankly at the bottom of the technical barrel.
You need to consider the bigger picture with this decision though. Do you have enough power and how can you be sure? If not, maybe you can get a Denon with XT32 for a relatively low price and think about getting amplification. If you have enough power, maybe put the money towards a better processor with ARC or Dirac.
There's another thing to consider though. When I went from v2 to v4, I found Audyssey made less of a difference. I still like it better with Audyssey engaged but it taught me that a more refined speaker plays nicer with the room. So maybe the active LFRs won't need EQ at all. So there's that but I know that doesn't make the decision easier for you.
Regarding power, I used to think I had plenty with my Onk because when I turned it up, it fatigued me and hurt my ears. What was doing the fatiguing though was not the volume but the distortion. The immense envelopment and emotion I get now with the ADAs is incredible.
Now that I wrote all of this, I seem to recall you have at least one ADA so you might have enough power.
