Balanced and unbalanced are NOT the same. A Balanced connection is handles interference better than a unbalanced signal.
Balanced does not mean 'stereo', and unbalanced does not mean 'mono'. One has nothing to do with the other.
If you are using long cable runs (over 10'), you would want to use the balanced connectors.
For more info, check out this web site:
http://homepages.enterprise.net/paul0blitz/techtip/art6.htm So, if your mixer has XLR (balanced) outs, and your amp has XLR (balanced) inputs, to get the best signal quality, use those together.
Oh, and welcome to the forum Freddie!