What is the difference between balanced (XLR) and unbalanced (RCA) connections?

In the vast majority of professional applications, only balanced connections are used. These are rather thick interconnects terminated with 3 pin XLR connectors as opposed to RCA plugs. High-end equipment often provides both connection types. Balanced connections cancel any noise injected in the line and may provide better sound than RCA connections. For this reason, you might want to listen to the component while switching between the two connection types and judge for yourself.