xlr vs rca

I understand it is better to used balance interconnects if possible. Is this always the case?

With good compatible XLR equipment YES - this is always the case. However connecting between low quality consumer RCA to pro-quality XLR is not always straightforward - check this out Ground loops are most often the culprit - this is probably one of the main reasons consumers report so much differences with interconnects - it is just not good to have stray ground voltages flowing through signal wires, as is done with RCA.

With the large amount of excellent SE gear it is hard to argue that balanced is inherently better in a home environment even though those that make it and use it would disagree.

SE gear is cheaper so it must be better - the savings can be used towards gold plated RCA connectors and ground loops are rare in the home... ;-) LOL

No hum, no ground loops and I am biamping.

Ground loops do not always show up as hum with volume turned way up with no music playing (of course really bad ground loops do). The insidious kind is when a power supply leakage affects ground on a device which adds modulated noise on your cabling as a function of power demands. The way to reduce this is to go balanced (so that the ground loop is induced equally in both positive and negative signals). You really can't detect this kind of insidious effect other than to observe the improved clarity of going to a properly balanced setup where grounds from different components are much less likely to get to your signal. The effect can of course be small when comparing good equipment that is well matched... nevertheless, several DB in better noise floor can usually be expected with XLR.

I’ve found it’s very often advantageous to float the ground at one end of the signal path.

Agreed that is often the first thing to try out....it stops the microamp ground loop currents flowing between the various chassis as well as still grounding the shield to give you better RF protection.

Balanced circuits are better at rejecting any noise from the power supply but your description of it doesn't make any sense. It isn't a ground loop problem.

You need to read up on what Whitlock says about the reasons why XLR balanced is so important for ground loops. Think about how a power supply fluctuates under heavy demand and how this may affect microampere ground loops between gear (the BIGGEST problem in audio as RF noise pick up on analog audio is much less common). Then realize that ONLY ONE wire in in an RCA circuit will carry this current flow on your signal wires - IT CANNOT CANCEL (as it does in well built XLR gear and cabling).

=> this is why a BIG BEEFY power supply is NOT simply about more power...often it can be more important for how much cleaner the backgroud or canvas upon which the music plays can become...

Perhaps I was not clear in the last post.....a BIG BEEFY power supply means less fluctuations due too the varying demand from dynamic music and therefore less ground loops from leakage to ground from the PS => less noise induced into the low level analog signals between components.

Try the Whitlock paper directed at students - Page 9 and 10. Although as the saying goes - you can lead a horse to water but...

In order to affect a ground loop whatever is doing it has to change the potential of the ground. How does a power supply do that?

Through parasitic leakage through capacitors and through transformers.

FWIW: There are plenty of examples where XLR has its share of noise and hum problems (poor design choices) and Whitlock covers these issues as well. So RCA can be better than XLR and vice versa depending on the setup and specific equipment. It is only properly implemented XLR that should have an edge over RCA.

I don't care what the textbooks say. I don't care how it measures. All I care about is how it sounds. Unfortunately there is no way to make that comparison via the internet.

Ok. Then it will be impossible to convince you. Perhaps the links will be useful to the original poster.

Traditional measurements illustrate how machines hear, not how humans hear.

Yes this is a good point. We may be discussing from incompatible and quite different perspectives/objectives. My perspecitive is audio reproduction with high accuracy. Most people may only be concerned themselves with what sounds subjectively nicer to them.

For example, it has been demonstrated that audio compression with the distortion and the reduced dynamics that it brings can be pleasing to the ear - making music sound more punchy and fat. So from a "what sounds best to me" perspective then any viewpoint can be valid. (Analog tape machines and certain circuit designs are highly prized for the sound they impose on the recorded music)

This divergence in goals is analogous to the difference between trying to follow a recipe exactly (reproduce what the cookbook calls for) or adding a bit of extra or different spices (not following the recipe rigorously). I want to hear what is on the recording. I appreciate that others do not necessarily seek that at all and it make for a discussion confusing.

As long as you and yours are beating the "it measures better so it must sound better" drum and I and mine are only concerned about what really matters, which is how it actually does sound, then there is really nothing to discuss.

No worries I get it. We have beaten this horse dead. I can respect that what concerns you is what really matters. I'll be the first to admit that accuracy in sound reproduction is what only a very small minority of hobbyists are after.