In deciding whether to go with XLR cables vs RCA cables, I was initially guided by Robert Harley in his complete Guide to High End Audio says (on page 215) “Many products offer the AES/EBU interface which is carried on a balanced line terminated with three-pin XLR connectors. Of these three conductors in a balanced signal, one is ground, one is the digital signal, and the third is the digital signal inverted. AES/EBU benefits from all of the advantages of balanced lines…and is transmitted at 5V, compared to the SPDIF’s 0p.5V. AES/EBU is usually the preferred interface because of this higher voltage, which confers greater timing precision, as well as greater noise rejection by virtue of the balanced connection.”
However, recently I read the following technical notes appearing on the Stealth Audio Cable site:
“There is absolutely no technical advantage in using balanced XLR instead of single-ended RCA with short cables (under several meters, and especially one meter), but still many people think, for some reason, that balanced is better, while in reality, balanced connection is only better with very long runs - 10 meters or more, or in turntable setups (especially from a phono cartridge, which is a balanced source by its nature, to the phono stage input).
The most common theory – which works well for me, because it coincides well with what I usually hear – is that single-ended connection (and gear) produces a natural spectrum of musical harmonics, same as in real life, while balanced gear (and connection) greatly reduces even (pleasant for our hearing harmonics), but leaves the odd (subjectively unpleasant, un-musical) harmonics virtually unmodified, unchanged, and thus DISTORTS the natural spectrum of harmonics, i.e. the ratio between odd and even harmonics, compare to life music.
A part of that theory is that our perception is less sensitive to the overall level of harmonic distortion (i.e. to the sum of odd and even harmonics) – than to the RATIO between odd and even harmonics. The same part of the theory explains why, for example, certain musical instruments sound “better” than others (why a Stradivarius violin sounds subjectively better than a modern instrument), and also explains why vacuum tube-based audio components usually sound more pleasing to a human ear than solid state, despite the overall level of harmonic distortion being usually several times as high in tube gear, compare to solid state gear.
The tonearm cable – from the cartridge to the phonostage – THIS IS where a balanced connection is superior (a phono cartridge is a balanced source, plus the signal is very, very small) – but, traditionally, contrary to the technical reason, most people use RCA cables with phono setups.
In general, I think that solid state units should have both balanced and RCA (for compatibility reasons), while tube gear should be RCA only: after all, the best sounding tube gear around - CAT, Jadis, Kondo of Japan - are RCA only.
However, while most equipment sounds better with RCA-terminated cables, it is true that some audio components do sound better using balanced XLR cables. NOT because the balanced connection is generally superior, but because of some other reasons, particular to the equipment.
Single-ended (RCA) and balanced XLR cables are different inside: RCA cables have one signal wire plus one shield/return, while balanced XLR cables have TWO identical signal wires plus shield (reference ground). Therefore, RCA and XLR cables cannot be converted to each other via just changing the ends.”
Despite the Stealth statement, it seems all of the cable manufacturers offer XLR cables in the one-meter length along with their RCA offerings, often at the same price but occasionally XLR is more expensive.
Curious to hear the opinions of the forum members on these two opinions.
Also, I read recently on this forum that in order for XLR cable to work properly, they must be connected to balanced equipment. But if manufacturers of gear offer balanced outputs and inputs, isn’t it presumed that the equipment is balanced? Otherwise, how would one know if the equipment is balanced. Thanks.