I'm in the process of upgrading my speakers and am considering doing so with JBL as I already have two older models that I was going to move and use as my surrounds and then replace the two fronts and the center. I have a good sub that I intend to keep. First question: Can I mix the N and S series without losing and tonal quality? For example I was considering some N series fronts with the S series center. Second question: Is there much of a difference between floor standing and bookshelf? If I go floor standing then I'll probably go with the N series. If I go bookshelf I'll probably use the S series. Any thoughts?