Balanced vs RCA between amp/preamp

Millercarbon hit the nail on the head

Horse puckey! I just got up, walked over to my handmade true-balanced end-to-end differential headphone amp, disconnected my Mogami XLR interconnect from my R-2r resistor ladder DAC and measured the pins on its standard Neutrik-branded male connector. ShOcKeR! All pins are the same length.

So I thought, well there’s *no*way* anyone would mansplain so authoritatively if they weren’t actually knowledgeable. Better give them the benefit of the doubt and find another cable with a non-Neutrik XLR connector on it. It took some digging, but I eventually found another cable with Amphenol XLR connectors. Nope. All the same length.

I’m going to trust Nelson Pass, Atmo-Sphere, and the electrical engineering professors who mathematically demonstrate how differential amplification (internally balanced components) are inherently better performing but also more difficult to engineer. Not a lot more difficult, but clearly complex enough to confuse your average solder jockey or audiophile store salesman.

Now, maybe some old Korean War era PA system cables used an early version of the standard with a longer pin, but they did a lot of things differently 60-70 years ago. Today, unless you can link to a whitepaper or standards doc that specifies a longer ground pin, I say we can safely assume the pins are the same length.

PS: When people say balanced is not inherently better, they mean that having a balanced circuit in a badly designed amplifier isn’t going to make that amp sound better than a really superbly engineered unbalanced amp. It doesn’t overcome an otherwise poor design.

This is simple. If both devices was designed for full balanced support then it is clear that XLR is preferable solution. If one of the device is single ended then RCA is perfectly normal.
I tested many cables and devices. This rule is in general pretty common. I I join my MC1.25 monoblocks with C2600 preamp with XLR and C2600 with Chord Dave with RCA since Dave construction is SE.
Simple as that.
Yea, sure. Different cables, hybrid devices, balanced architecture implementation can effect the sound eventually but the rule more or less remain.
One of the earliest posts was that XLR is for long distance connections. True, but super HIEND equipment will benefit from it as well. If I adjust the position of my speakers by half of inches and I hear it then why extra clarity provided by XLR should not have the same influence.
Over 20thy years of adventure with audio teach me that there are no boundaries in this hobby.

I began my transition from rca to diff balanced kit 2 decades ago.

Same nonsense appears here as back  then (that they are ONLY for long runs) I have heard differences between 0.5m and 1.0m XLRs

Dif balanced is basically 2 totally independent channels (hense doubling the cost), though they often incorporate the same output transformers. 

EVSs new EVS 1200 has 2 separate channels in it whereas most of the similar class D stereo amps do not. Appreciating his knowledge, I bought one

Buyer Beware:  I used to call out the hi end mag editors for giving dif balanced kit to 'reviewers' whose systems are NOT dif balanced. I finally gave up. 

A lot of kit has XLR I/Os but the kit itself is NOT dif balanced, therefore the listener will not hear the difference

RicEVS, wrenth,  and engineears have it correct

Also prefer balanced cause I’m not a fan of single ended cables use of the ground screen to carry 1/2 of the signal. I theorize that this is why there is so much more variation in sound from one type of cable to another vs balanced xlr where the shield is separate from signal carrying conductors