Balanced Interconnect Recommendations

If the circuit topology of your components are not fully differentially balanced from input to output then there is zero sonic benefit of using balanced ICs.

While this belief is held by many audiophiles, and I believe it is true in the majority of cases, I would not consider it to be a hard and fast rule. It is certainly possible, IMO, that a balanced connection between components having unbalanced internal signal paths (i.e., components that are not "fully balanced") may sound better than an unbalanced interconnection in some or many cases.

Why? There are a number of potential reasons, depending on the designs of the specific components being connected as well as on the cable that is being used:

1) When the interconnection is changed from RCA to XLR or vice-versa the configuration of the interface circuits that are being used in the two interconnected components is being changed;

2) Susceptibility to ground loop effects is being changed. Ground loop effects can cause a multitude of subtle sonic effects, not just hum. And those effects will tend to have little if any predictability, as they depend on factors that are usually unknown, such as the internal grounding configurations of the two components, and on whether each component connects the shields of the cables to circuit ground or to chassis, and on how circuit ground and chassis are interconnected in each component. Both technical factors and my perception of anecdotal evidence that has reported over the years suggest that balanced interconnections are usually less susceptible to ground loop effects than unbalanced interconnections;

3) In many cases input and output impedances will be different;

4) In many cases overall system gain will be increased by 6 db with a balanced connection;

5) Sensitivity to cable differences will be reduced or eliminated in the case of balanced interconnections if the interface circuits in the equipment conform to the AES48 balanced standard Ralph (Atmasphere) has often referred to;

6) And speaking more generally the basic operating principles of the two kinds of interfaces are different.

7) And of course the cable is different.

***None of that has anything to do with whether or not the internal signal paths of the two components are balanced.***

And a lot of that doesn’t have much if any relation to the lengths of the cables or to the noise environment either.

As is often the case in audio, the only way to know for sure in a specific system is to try it both ways.

Regards,
-- Al

@almarg   So your contention is that the benefit of common-mode rejection inherent to an XLR connection may provide an advantage over single-ended connections in some cases?  I'm not sure common-mode rejection is the most important factor to be weighing when selecting cables but I can't disagree with you 100% either (only 99.9% ;-)).  For instance if you're talking about a short length and a low-gain signal then a single-ended circuit may very well outperform balanced regardless of common-mode rejection.  This discussion feels more theoretical than practical and it sounds like we both agree that the vast majority of the time the user is much better off in terms of both cost and performance to only go with XLR when engaged with  fully balanced circuit.  And agreed, if you don't mind spending the money and investing the time, sure it never hurts to try both ways.  I just think there are higher odds pursuits to improve audio quality.

So your contention is that the benefit of common-mode rejection inherent to an XLR connection may provide an advantage over single-ended connections in some cases?

No, that is not what I was saying.

By "common mode rejection" I assume you are referring to rejection of common mode noise, i.e., noise that is picked up equally in the two signal conductors of a balanced cable, which can therefore be rejected or at least attenuated by a balanced receiver circuit.

But note that none of the seven factors I referred to have anything to do with that, except perhaps to some extent in the case of number 6.

Regards,
-- Al

@almarg   The reason that balanced lines are going to be more resistant to noise is due to common-mode rejection so I assumed (incorrectly) that's what was underlying your points.  And yes, you referred to common mode rejection exactly in the way I meant as well.

Perhaps someone(s) on this forum who is using unbalanced circuits could do a comparison with RCA vs XLR IC to see if it makes a sound quality improvement in their system. My main system is fully balanced from input to output and I use XLR's only due to that topology.  My second system uses an integrated amp...otherwise I'd volunteer!

Real life experiences ...
I have the REGA OSIRIS integrated amp and the REGA ISIS VALVE cdp/ dac.

(1) REGA itself recommends balanced XLR interconnects between them . I stress-tested
their manual Recommendations with shoot-outs between high-end RCAs versus XLRs ....in my shootouts, REGA was right .

(2) In direct cable bake-offs in MY system (emphasis added ...) against numerous high-end brands, NORDOST FREY XLRs were best of breed at their price points.

(3) Completing the NORDOST cables array with NORDOST FREY shotgunned speaker cables and matched jumpers was a further audio performance improvement.

I would like an eventual further move up to NORDOST VALHALLAs , but budgets are always a limiting factor.

highly recommended .