Balanced XLR vs. Unbalanced RCA ?

Any advantages to either cables?

Thanks

XLR's are balanced with a third wire to ground them and prevent picking up any external interference. RCA's do not have this and thus may pick up things like stray RF. Granted short runs are not likely to pick up interference and XLR connections do take up more space and also cost a bit more. I have heard a speaker pick up a radio station through a long run of wire which could have been prevented by balanced connectors. A lot of the advertising you see for extensively shielded RCA interconnects exist because there isn't much else you can do to make an otherwise cheap and common connector cutting edge, more expensive, and...oh yeah, less vulnerable to outside interference..

IMO balanced XLR don't sound as good as unbalanced RCA. Balanced mode signaling requires two set of signals, one complimentary of the other. Balanced amplification works by taking the difference between the two complimentary signals. Balanced signaling requires two sets of signal paths which includes cables, traces and amplifier circuits. Each set of signal path adds amplitude distortion, phase distortion and phase differences between the two complimentary signals because no electronic circuit is perfect. With phase differences, one of the signal is lightly ahead or behind the other. With all these errors coming into play, the differential signal is now badly messed up.

There are opposing schools of thoughts out there. There are those who believe in balanced circuitry all the way from source to speaker output and those who believe that single ended signaling is the way to achieve signal purity. I am of the latter. My argument is that it is impossible to design a perfectly balanced circuitry with zero phase and amplitude error.

The benefit of balanced signaling is immunity to common mode noise. Balanced signaling actually originated from professional recording use where microphones had long cables length and low signal level. This problem is not significant with modern day amplifiers because of the high signal levels compared to microphone and short trace length. Basically these noises are almost non-existent. By using differential signaling, the phase and amplitude distortion is about doubled because of the two circuits. It does not make sense to add distortion with no additional benefit by using balanced signaling. So in my opinion, unbalanced RCA beats balanced XLR hands down.