I have some interest in replacing the Pioneer with a pre that has balanced outputs to connect to my Parasound A51. I have read numerous reviews that make an emphasis how much better halo amps sound with balanced versus unbalanced cables. (I am skeptical for several reasons and would appreciate anyone who can provide some feedback).
The technical difference between balanced and unbalanced cables is real, due to the potential advantage of common mode rejection in differential signaling. The practical issue is, as ADTG points out, whether or not the advantage is audible.
For cables there are two factors. First is cable length. For a few feet of interconnect cabling you are very unlikely to hear any differences. On the other hand, if you're like me and use 45 feet of cable between your preamp and amplifier the potential advantages of balanced cables are much greater, and might be audible. The second factor is the environment the equipment is in. Some people live in areas where there is a lot of electromagnetic interference (San Diego is a good example), and others don't. How close are broadcast transmitters and military facilities, for example?
Balanced cables also have the advantage of using a much better designed, robust, and easier to use connector. So-called RCA connectors and jacks are prone to wear and stress, while XLR connectors, being intended for pro-audio, are better suited for numerous plug/unplug operations. For these reasons I like balanced connections even when there isn't an audible advantage.
In the amps and preamps themselves the balanced connections are often implemented with better-designed circuitry than the unbalanced connections. For example, many amps have double the input impedance on balanced inputs. For long connections or challenging EMI environments this can improve signal quality to the point of audibility. And oftentimes preamps or source components have a lower output impedance on balanced connections too, which is also better for good signal transmission.
Of course, as ATDG would point out, even with all of these advantages you may not hear any differences between balanced and unbalanced connections in your system, and clearly he doesn't. On my tests for short cable runs, even with equipment that I know has a better balanced implementation than an unbalanced one, I couldn't hear the difference either. I haven't experimented on my 45' cable run, so I can't comment on that. My bottom line is that if you can quantitatively prove an advantage for a design strategy you should use it, because sometimes insignificant advantages can add up in a system (of any kind), and simple audibility tests of any one factor may not be revealing enough.
And if all else is unconvincing, I like the secure "click" of a nicely made Neutrik connector a whole lot better than I do fighting with a poorly conceived RCA connector.
