xlr vs rca

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.

If your amp and preamp is true balanced then go balanced as much as possible. If it is not then I think it is a waste of time and money.

Herman brings up a good point. Traditional measurements illustrate how machines hear, not how humans hear. I too was convinced by all the reading I did that a balanced set-up would have advantages over single ended, and it may have, but I could not really hear a difference, especially with the critical factor I was benchmarking against which was reduced noise floor.

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.

{edit} I was writing this below as you posted so I had not read your last response. I agree, we are approaching this from 2 different angles {edit}

I know I said I was bowing out but I wanted to address your comment about convincing me. Of what? That balanced circuits have some inherent advantages in the area of noise performance or that because of these advantages balanced must sound better?

The former is a given, the latter is not. It is easy to fall into the same trap that Julian Hirsch did when he proclaimed the superiority of transistor amps that had extremely low measured distortion. They measured well but sounded like crap. The same trap that some fell into when CDs were declared to have perfect sound forever. It is easy to develop tunnel vision and focus on this one tiny area (noise performance) but the picture is so much bigger. If all else was equal would it be better to have the inherent advantages that balanced offers? Of course, but since it is not all equal the point is moot.

The proof is not what is in the textbooks but in what we hear. The type of system I listen to brings me pleasure that others I have heard do not. I've heard systems that have a low level hum that is easily heard at the listening position but when the music was turned up they sounded glorious. Sure, it would be better to get rid of the hum but if you sit there tapping your toe with a smile on your face how much does it really matter?

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.