I will have to agree to disagree with Erik here. While many love room correction, I have not had good results with it. I have worked with super high end Dirac Live processors as well as low-cost receivers. In either case, the audio just sounds more natural to me without automated room correction. Manual EQ can be helpful, if you know what you want to do.
Since your primary goal is music sound quality, I will agree with Erik on this point to buy the best speakers you can for left/right. Go for at least the Silver 300 model if you can, which has a dedicated and better voiced midrange (very important for music). The Silver 300 shares the same tweeter as the Bronze series, so voicing will not be that different for anything above 3khz (not as bad as combining two separate speaker manufacturers).
From a Home Theater / Movie standpoint (which is my primary goal), I feel that matching the voicing of the three front speakers (left/center right) is very critical. Matching the surround speakers is not as important here, but it’s a "nice to have". The absolute most important speaker for home theater is the center channel. That’s what I would upgrade first, then follow the left/right upgrades when I could.