At what distance are balanced XLR cables needed?

Kal, Absolutely. Why not to use balanced if environment is known to be noisy. My Rowland 102, a class D amp, has only balanced input connector - a mature decision on a side of Jeff Rowland. Balanced has also two practical advantages - it won't disconnect (latch) and prevents touching input (exposed side always female with recessed sockets). The only disadvantage I know of is a little higher price.

IOW if you can hear differences in the cable between the line section and the power amp, then the cable is not being controlled.

Hmmmm, now there's a pretty serious generalization. I have heard significant differences between IC's in the critical line-stage to amp link with Audio Research, CAT, BAT, Aesthetix, Aria/Counterpoint, to name a few products. Are you claiming that the designers of these products are not competent to "control" the cable?

Mariv26: Anything over 3 meters, but I would still keep the interconnects as short as possible

I don't think you can make such a general recommendation

Agreed, as my own experience voids such a generalization.

I have heard significant differences between IC's in the critical line-stage to amp link with Audio Research, CAT, BAT, Aesthetix, Aria/Counterpoint, to name a few products. Are you claiming that the designers of these products are not competent to "control" the cable?

Actually I was restating something Ralph Karsten restated in this thread:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1276356977&openflup&531&4#531

It is 8 paragraphs into the response if you include the numbered paragraphs.

Personally, I think Ralph has been on to something for a while. There is some credence to supporting the 600 ohm standard in balanced designs. Not many manufacturers do. This does not make them incompetent, but it does allow the cable to exert an influence on the signal. As for single ended designs the ability to design components to control the cable is more difficult. As Ralph states in the first sentence of this response to me in another thread:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1276356977&openflup&537&4#537

Driving a load of less than 1000 ohms is not an easy task. So it makes sense that in single ended designs you could more easily hear differences in cables.

FWIW, I hear very little difference in cables in my system these days. I've sold off all my Stealth and other uber expensive cables and am running very modestly priced cables in my system. There's not much I'm missing IMO. Allowed me to to put more money in my components as well.

If I can make some comments?

To clarify, the balanced cable can run as long as you want it to and the cost of the cable will have no bearing on the sound if:

The equipment supports the 600 ohm standard. If this is true you will not be able to hear any differences in cable, regardless of length.

Now this is not true of all high end audio equipment. Most of it does **not** support the standard, and so as a result people are still hearing differences in balanced cables.

The balanced standard was developed specifically to eliminate this problem! So you can see, supporting the standard is important if you want to eliminate the artifact (or 'sound') that all cables have. And yes, many well-known companies don't support the standard, and as far as I can tell, don't seem to know that one exists.

"cost of the cable will have no bearing on the sound if"

Can you explain why purity of metal becomes unimportant in balanced configuration?