Just do a search about this (Google it). Or check here at Audioholics in the Articles section. Or check at Secrets of Home Theater and High fidelity.
Or check at The Absolute Sound. Or check at stereophile.
And no, you don'y need balanced connections if one of your component doesn't have it, you just used the unbalanced ones.
* In brief, Balanced is probably not needed in your case, unless you have two components (pre/pro and amp) with both balanced connections, and they are separated by quite a large distance. And normally the cheaper components with balanced connections are not truly balanced and can produce worst results than unbalanced ones.
Balanced (XLR jacks with 3 pins, one for the ground) vs Unbalanced (RCA jacks) is more a selling feature than a truly useful one.
Truly balanced cables and components are mainly used in professional recording studios. Personal home theaters rarely used them, unless they are truly balanced on both ends (quite expensive) and that the cable runs are quite long, say 5 meters and more.
Bob