What's better: RCA or XLR?

What is better; RCA or XLR connectors and why? With some brands of cables, the RCA plug cost more than the XLR, Why?
My System: Classe CA300 amp
Classe cp50 Pre-amp
Classe cdp .5 cd player
BW Nautilus 804 speakers
Usually XLR will give you a lower noise floor, that's the big benefit. I've seen some cables (transparent for instance) that charge roughly double for XLR vs RCA becuase they are running extra wire for the 3rd leg of the balanced run. I use all Transparent XLR and love it, but cables are system dependent.

I've heard on shorter cable runs, XLR makes less of a difference, longer, much more pronouced...
Balanced is better because you lower the noise floor and get 6db's of gain and usually cancels out any hum that your system may have. Most high quality cable already has the negative conductor inside and you can just add the XLR's yourself.
Ask someone who knows Classe well. I agree with the prior threads; that XLR is usually better. Some brand, as Krell (which I use), it makes a huge difference...XLR far surpassing the RCA.

Sonically, I've compared mid-priced Syn. Res. RCA and XLR ICs and with 40" lengths I preferred the sound of the RCA. It's definitely one of those personal preference things though. With long IC runs (20-30 ft. or more) apparently XLR has some worthwhile advantages. Cheers. Craig
XLR better in EVERY case if gear runs true balanced. Single-ended is a compromise of signal integrity to save money. No other reason for implementation of single-ended design and cable. Cheaper, that's it. Balanced maintains true signal, higher gain, lower noise, better dynamics. If electronics are not true differentially balanced, you're not gaining any signal integrity, only noise cancellation over long runs.
It depends on the equipment. Some manufacturers use XLR connectors w/o really using balanced circuitry so in such cases, there is no improvement in using balanced cables. I use balanced between my Krell amps and a Wadia cd player and have noticed that background noise is much lower. Plus, I live in San Fran where RF is big problem like most large cities.
Since Joeb's post seems to me NOT about the difference in sound between balanced or unbalanced ICs but about the difference of XLR and RCA connectors, I must say, that I personally prefer XLRs to RCAs, although I cannnot really discern any difference in the sound. I prefer XLRs male and female, because they often give a better fit, are easier to solder, are more easily cleaned and more rugged in case of rough handling. No wonder they have been the connection of choice for professional use for years now. If after all, you would insist on a difference in sound, I often have the impression that XLRs are quieter ( also unbalanced ), but that may well be my imagination, rewarding me for the job of having unsoldered RCAs and put in XLRs.
There is a reason that pro sound and recording studios run balanced. But, I guess the main thing is less noise and signal loss with long interconnect runs. Another reason in pro sound is the ability to hook cables together when longer runs are needed.

Joeb asked what was better RCA or XLR connectors. In high end audio, sound/music qualities are paramount, so that should be the primary consideration. No? Prior to purchase of ICs, I discussed this issue with a Synergistic Research Tech., and he said he preferred the more organic, rounder, more liquid and "whole" sound of RCA ICs. But he also said that most (not all) of the people he worked with, and were into audio, used and preferred XLR connectors.

I had no preconceived biases for one over the other, and having both fully balanced pre-amp and pre-amp (also single ended), I tried both (SF Line 2 and McCormack DNA2 DX). I found that music with the different ICs (same model though) was as the Syn. Res. Tech described it, and that XLR sounded dryer, leaner, and more detailed (musically). I ended up purchasing RCA ICs for the music quality/character. My ICs were only 40".

As to the robustness of the plug and connection security, I would prefer XLR, but that is seldom a problem in home audio. There are advantages for pro use though, and especially if long runs are used. In fairness to the XLR terminals though, I did not give them much of a chance to break in whereas the RCA terminals were well broken in.

IMO, the only valid comparison should be A to B of the same ICs in RCA and XLR and with well known music. Try it and see. As to professionals using only XLR, well, they have professional reasons, but musically these pros produce some really excellent recordings, and they also produce some really lousy recordings. But I don't really believe the end product is very dependent upon the type of IC used. Cheers. Craig.
Great post Craig, must try listening for what you describe.
I fully agreed with Madisonears and SFstereo. Your equipement MUST be balanced from input to output to realise the benefits of XLR over RCA.
Let's be clear about XLR & Balanced first.

The XLR is a *type* of connector.

It could be used for almost anything, and has been. It was developed as an audio connector for 3 wire balanced signals.

The RCA is a *type* of connector.

It could be used for almost any use, and has. It was developed as a consumer type coaxial connector.

The reason some RCA plugs and jacks used for *audio* today are more expensive than XLRs (built mostly for pro audio and broadcast) is simple enough. The XLRs are made in very large quantities and not of exotic materials (possibly excepting one XLR intended for high-end audio I saw). Whereas the RCA components you see for high-end audio use are made in relatively small quantities and use exotic metals and/or platings and insulators (teflon for example).

Similarly, the construction and manufacture of finished cables for *high-end audio* is also a low quantity process utilizing high cost components when compared to commercial cables made for the broadcast and pro audio industry, so the prices are higher in general.

The use of *balanced* lines for audio is another matter entirely. The use of balanced lines for audio gives you a reduction in potential noise and hum due to something called CMRR (common mode rejection ratio) which is the cancelling of signals that are impressed upon the wire (picked up) from external sources (hum, noise, RF, etc.).

(CMRR is *not* an attribute of the wire, but of the receiving circuitry - if the circuitry doesn't do this right, or is not balanced electronically, the CMRR degenerates back to no better than single ended, or worse)

The single ended connection does not have this immunity and depends upon sheilding alone. Often this is not a problem since in practice this is a problem under two circumstances:
1. Loooonnnnngggg runs of wire
2. Low levels of signal over longish runs

The second is found with microphones (similar to phono carts in signal levels) to be a significant problem. A typical PA system or studio must because of the physical requirements have very long runs with signals of all levels going back and forth. So runs of as much as a hundred feet or more are not unusual. Contrast that with the 1m run between your CD and preamp!

Studios and PA systems use 600 ohm balanced lines to overcome the problems of hum & noise as well as HF rolloff over a long cable run.

Which is better? In theory the balanced cable is better when driven with a balanced signal and recieved with a balanced input,better yet if it is also 600 ohms (low Z).

In practice this also means *more components* and more "things" for the signal to pass through, so may not actually be better, or worse than the RCA/single ended cable IN THE APPLICATION we are discussing (your system).

Thanks to all who responded. the technical viewpoint is relevant, however, my main concern is, as someone suggested, the difference in the "quality of the sound". There seems to be so many different views on both sides of the question. My only experience with cables is this. I have a pair of Harmonic Tech XLR pro-silway from amp to pre, and it replaced a cheap set of rca's. I heard no difference, although I must admit I didn't do a lot of critical listening comparing the 2. However, when I replaced the cheap rca's from cd player to pre-amp with a set of Cardas quadlink 5c RCA ends there was a noticeable improvement.
thanks, joe
Very good clarification by bear regarding the XLR vs RCA connector. I would further clarify that XLR I/Os could be installed on the chassis of any component that was unbalanced in nature, and simply bridge the pin configurations for true unbalanced operation. That being said, I feel that the RCA connector was a very poor design that quickly deteriorates after repeated use. The lack of any locking mechanisms, to insure stability and reliability, seem rather amatuerish as an industry standard to me. Its no wonder the original Mark Levinson gear insisted on Fischer/Camac type connectors. He saw the problem and adressed it.It was unrealistic, since all other equipment lacked these, so interface was always through more RCAs. It was like having a 24 bit machine with only 16 bit discs to play through it.............Frank
I concur with Saki winki.
While it is usually best to have a fully balanced system I did get rid of a hum problem that I had with my amp by putting XLR's on the amp end of my interconnects and leaving RCA's on the preamp end. I eventually added XLR outputs to my preamp. Even though it is not a balanced design, I like the better connection that the XLR's make.
I have found the shorter and less complicated the signal path the better.Single ended have a less complicated path than balanced.Single ended I sense to be more coherent.
I had similar set-up about 6 months ago definitely go with the XLR it is more quiet background and dynamic.
Depends on your components. The designs of balanced outputs can vary greatly.

Balanced connections have two signals, a positive and a negative signal, which are inverted versions of each other. They carry the signal currents. At the destination, these are subtracted from each other to create the signal. Any noise that is the same on both cables will be subtracted-out. There is also usually a ground that does not carry signal current - it's function is to force the grounds in the two components to the same potential. The ground conductor can be a wire or an overall shield surrounding the other two signal conductors.

Unbalanced or Single-Ended connections have a signal and a ground RETURN. Both of these carry current and the signal is driven at the source with the return current flowing back to the source on the ground conductor. The ground conductor can be a wire or a coaxial shield, depending on the design.
Well stated. The best balanced component uses mirror imaged circuitry. But, designers have switched to balancing transformers such as Roland Research.