Balanced vs. Unbalanced - What does it mean?

This is one of those threads that can go on forever as there is no real answer. As has been pointed out it is system dependent. There is little or no agreement among the most experienced designers and reviewers. Martin Colloms, who has tested about everything for 30 years has said that 95% of the components he tests sound better single ended and that balanced best use is in long runs in studios. BUT, he uses VERY expensive ICs. A recent article by a recording industry professional in HIFICRITIC mag. , which Colloms publishes, came down on the other side. The author maintained that equal results could be obtained with much cheaper cable with balanced. At the same time he pointed out, as mentioned above, that not all "balanced" are created equal and that standards about how it is implemented are very imprecise, a situation not unknown in other area of audio. He also recommends transformers in some cases. He notes that balanced seems to be popular in US and Japan but not Europe, which he finds strange. So the answer seems to be dependent on each system and user, another not unusual finding.

Some electronics are designed single ended with balanced operation included so that the buyer would think that the component is a greater performer. The truth is that those circuits that are designed single ended with XLR options sound the same in either configuration. Circuits like those that are designed around a balanced circuit such as Ayre will greatly benefit from balanced operation, although single ended operation is available for convenience.

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I don't know or understand the difference and I really don't care. All I really care about is how either will sound in my system. However, I tried both single ended and balanced. Balanced sounds better in my system.
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Thanks for the information everyone and Almarg - thank you for the links.

Has anyone compared balanced to unbalanced on the McIntosh MC402 Amp?

“Line-level” signal level for consumer audio equipment is nominally -10dBV (0.32V RMS). However, “line-level” signal level for pro-sound equipment is +4dBV (1.23V RMS). Simply put, pro audio gear is looking for a 14dB higher signal level.

Anyone who suspects that 14db additional signal level will likely translate into significant benefits in dynamic range would be correct (never mind the length of your audio cables). Most electronics does not perform as well at very low signal levels. Of course, it won't matter much for a hyper-compressed Green Day album but on a good recording you'll often notice a small or slight difference with balanced.

Also the "hum" that Al mentions is even more of a significant problem when using lower signal levels - not to metion the lack of shielding and the problematic grounding of chassis when using RCA. Serious audiophiles really should consider balanced before investing in things like resonator cups, as there is science as well as a long track record behind balanced XLR equipment.

Nevertheless be careful. Pro audio gear will often be too "hot" for consumer grade stuff and you'll get clipping unless you attenuate pro quality balanced signals when interfacing to ordinary consumer grade gear. RCA is ubiquitous ONLY because it is cheap and often adequate.