I had my new home wired for a 5.1 system by the builder.  I uncovered the wall plates today to find out that he wired cat5 to each of the 4 sat. speaker locations and a coax cable for the subwoofer.    Is this normal?  How do I take the twisted pairs and connect them to my 522D's?  And for the sub type F connector on one side to a rca on the other?  Do they even make that kind of cable?

Thanks