Single ended to balanced conversion....

[Primalsea]

Everything has been pretty well covered but I would add that the input impedance of balanced circuits is usually lower than unbalanced, so the preceeding equipment will need to be able to dive the load. This is rarely an actual issue as most equipment can handle this additional anyway, but in some cases can result in increased distortion. In real life this is not usually a real issue.

Also balanced nominal line level voltage is a fair bit higher than unbalanced nominal line level. In some cases this can be helpful as you can crank your volume up abit further than if you were going into an unbalanced amp. I find that some equipment sounds better cranked up a bit.

[Barry]

Actually, at the risk of putting the OP right off the idea of feeding a balanced power amp from an unbalanced preamp, there is one more complication, and it's this:

Is pin 1 ground/earth or 0V? Depends what you mean by ground. The amplifier's metalwork should be earthed to the mains for safety (unless it's double insulated). That doesn't mean it has to be connected to 0V though. So what do you do with the little earth tag inside the XLR connector? It's there so you can make a link between the XLR's metalwork and pin 1 if you want to. But do you want to? If you do make the link and the amplifier's casework is connected to 0V then you're making a link between mains earth and 0V. Is that a good thing or a bad thing? Depends on how the preamp is wired. Is the preamp's 0V also connected to mains earth or is it floating?

It would be nice if balanced equipment actually did live up to its goal - that you can connect anything to anything and there'll never be a problem - but things don't always work out like that.
Having said all that, I'm not claiming that there's trouble ahead for the OP. Just wire up an RCA-XLR cable and see what happens. Most likely there won't be any problem at all.

Sorry - I was being sloppy with my terminology. Yes Pin 1 is 0V or the signal ground, whether that is the same as the mains earth will depend on the design of the amplifier. Certainly the housing of the receptical will be earthed as it is connected to the case metalwork, so the shell of any plug mated will also be earthed. When it comes to the 'little earth tag' inside the shell, I don't use them, the shells are electrically safe and there is no possibility of creating an earth loop.

I'm a big believer in the idea of using balanced-line systems. If the equipmant is designed to be fully dual differential, there are noticable benifits to be had. There is no a priori reason why they should be any noisier, or the impedance should be lower, than with unbalanced systems; 600 Ohms is a legacy from the telecoms industry.

I use them because I have balanced input monoblock amplifiers located behind each speaker and run 15m lengths of balanced-line cable back to the preamp (which has fully balanced outputs), which in turn is fed by a CD player also having fully balanced outputs.

And since pick-up cartridges are inherently balanced devices, I am looking for a phonostage that is also fully balanced, but haven't, as yet, found anything suitable.

[Pharos]

Yes balanced is reliably very good, but often has a theoretically doubled distortion, although this is already so low these days that it is still near zero. (AVI pre 0.0001%, ATC pre 0.0002%)